when and how do you use Self?
I am new to python, Could someone explain (in English) how and when to use self? I have been reading, and haven't found a good example/explanation Bruce Tieche ([EMAIL PROTECTED]) -- http://mail.python.org/mailman/listinfo/python-list
Re: Getting a function name from string
On Wed, 02 Nov 2005 19:01:46 -0500, Mike Meyer <[EMAIL PROTECTED]> wrote:
>"Paul McGuire" <[EMAIL PROTECTED]> writes:
>> "David Rasmussen" <[EMAIL PROTECTED]> wrote in message
>> news:[EMAIL PROTECTED]
>>> If I have a string that contains the name of a function, can I call it?
>>> As in:
>>>
>>> def someFunction():
>>> print "Hello"
>>>
>>> s = "someFunction"
>>> s() # I know this is wrong, but you get the idea...
>>>
>>> /David
>>
>> Lookup the function in the vars() dictionary.
>>
> def fn(x):
>> ... return x*x
>> ...
> vars()['fn']
>>
> vars()['fn'](100)
>> 1
>
>vars() sans arguments is just locals, meaning it won't find functions
>in the global name space if you use it inside a function:
>
def fn(x):
>... print x
>...
def fn2():
>... vars()['fn']('Hello')
>...
fn2()
>Traceback (most recent call last):
> File "", line 1, in ?
> File "", line 2, in fn2
>KeyError: 'fn'
>
>Using globals() in this case will work, but then won't find functions
>defined in the local name space.
>
>For a lot of uses, it'd be better to build the dictionary by hand
>rather than relying on one of the tools that turns a namespace into a
>dictionary.
IMO it would be nice if name lookup were as cleanly
controllable and defined as attribute/method lookup.
Is it a topic for py3k?
Regards,
Bengt Richter
--
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Re: Microsoft Hatred FAQ
John W. Kennedy wrote: > IBM was genuinely innovative, and did their best to provide value for > money. Microsoft hasn't been able to produce anything but me-too > products since the 80's. (Multiplan, Word for DOS, the QBASIC engine, > early sponsorship of mouses, and the gutsy decision to morph MS-DOS > 1.0, > a CP/M quasi-clone, into DOS 2.0, a Unix quasi-clone, are about all I > can give them credit for.) You're suggesting MS stands for 'Mimick or Steal', right? -- http://mail.python.org/mailman/listinfo/python-list
Re: when and how do you use Self?
"Tieche Bruce A MSgt USMTM/AFD" <[EMAIL PROTECTED]> wrote: > Could someone explain (in English) how and when to use self? > > I have been reading, and haven't found a good example/explanation consider a class C: >>> class C: ... def method(self): ... print self ... >>> C you can create unique instances of this class by "calling" the class itself: >>> a = C() >>> a <__main__.C instance at 0x00925FD0> >>> b = C() >>> b <__main__.C instance at 0x00927030> here, "a" and "b" are two separate objects, that both refer to the same class object, but are otherwise distinct (the cryptic codes are object identities). now, if you call a method on one of those objects, Python will use the method code from the class, but the method will get a reference to the instance as its first argument (self). when you call the method via the "a" object, the method gets a reference to the "a" object as the first argument: >>> a.method() <__main__.C instance at 0x00925FD0> when you call the method via the "b" object, the method gets a reference to the "b" object as the first argument: >>> b.method() <__main__.C instance at 0x00927030> the instance object is usually used to store instance-specific variables (usually known as "attributes" or "members"). an example: >>> class Counter: ... def __init__(self): ... self.value = 0 ... def increment(self): ... self.value = self.value + 1 ... return self.value ... >>> a = Counter() >>> b = Counter() >>> a.increment() 1 >>> a.increment() 2 >>> a.increment() 3 >>> b.increment() 1 (the __init__ method is automatically called for each new instance) you can also access the instance attributes "from the outside": >>> print a.value 3 >>> print b.value 1 for more on this, see: http://docs.python.org/tut/node11.html#SECTION001130 -- http://mail.python.org/mailman/listinfo/python-list
Re: when and how do you use Self?
Tieche Bruce A MSgt USMTM/AFD wrote:
> I am new to python,
>
>
>
> Could someone explain (in English) how and when to use self?
>
Don't use self. Use other.
--
bruno desthuilliers
python -c "print '@'.join(['.'.join([w[::-1] for w in p.split('.')]) for
p in '[EMAIL PROTECTED]'.split('@')])"
--
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Re: how to write a blog system with Python
ice wrote:
> I am a fresh here , and I have no idea of it.
> Do you have any comments?
>
Learn Python
Learn web programming
Write the specs for your blog system
Design the solution
Implement it
--
bruno desthuilliers
python -c "print '@'.join(['.'.join([w[::-1] for w in p.split('.')]) for
p in '[EMAIL PROTECTED]'.split('@')])"
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Re: Python and MySQL
I am also have _mysql.c that has to be compiled. I downloaded 1.2.0 from here http://sourceforge.net/project/showfiles.php?group_id=22307&package_id=15775 (the .tar.gz). Do you mean, that if I drop the import _mysql and from _mysql import ... lines everything will work OK? I "private install" would be great for me, if it works :D -- http://mail.python.org/mailman/listinfo/python-list
OT - Re: Microsoft Hatred FAQ
David Blomstrom wrote: > "Everytime someone compares MS's behavior with some > less controversial criminal behavior, you act like > they > accused MS of holding people up at gunpoint." > > Screwing literally millions of consumers and taxpayers > and holding entire schools hostage is far worse than > holding up an individual at gunpoint. The name > Microsoft is virtually synonymous with crime, even if > many people are too stupid to recognize it as crime - > or the courts are too corrupt or inefficient to > convict Bill Gates for many of his crimes. A) I don't much care if people wander off topic from time to time - that's what filters are for. But as a matter of general courtesy is it too much to ask that the subject line be so marked? B) Rhetoric is not Reality. "Crime" has a very specific definition. It always has one or more of Fraud, Force, or Threat. No such case against Microsoft has ever been levied. Just because *you* don't like market outcomes doesn't make it a "crime". Here is some *thoughtful* counterpoint (instead of the ignorant foaming that has characterized this thread): http://www.cato.org//pubs/pas/pa352.pdf http://reason.com/0111/fe.dk.antitrusts.shtml http://www.cato.org//pubs/pas/pa-405es.html C) Hate Microsoft all you want. But those of us old enough to have actually done this for than 10 minutes recall the days where every single hardware vendor was also a unique software and systems vendor. Absent a Microsoft/Intel-style de facto standard, you'd never have seen the ascent of Linux or Open Source as it exists today. Drivers are painful to write, so oddball or vendor-specific systems don't get them very rapidly. Microsoft/Intel commoditized the space whether you like it or not. They (perhaps unintentionally) created the computer equivalent of "standard connectors" as found in audio systems. D) Your ranting is puerile. If you are going to waste bandwidth on OT matters, at least make it intelligent and/or interesting. E) I prefer Unix and its variants. However, I (and you) are direct beneficiaries of Microsoft's success. F) There are *more* choices than ever today for both systems and applications software. Stop foaming, and go do something useful with them ... No Cheers, -- Tim Daneliuk [EMAIL PROTECTED] PGP Key: http://www.tundraware.com/PGP/ -- http://mail.python.org/mailman/listinfo/python-list
Re: how to write a blog system with Python
ice enlightened us with: > I am a fresh here , and I have no idea of it. Do you have any > comments? Look up "turbogears" and watch the "20 minute Wiki" video tutorial. Sybren -- The problem with the world is stupidity. Not saying there should be a capital punishment for stupidity, but why don't we just take the safety labels off of everything and let the problem solve itself? Frank Zappa -- http://mail.python.org/mailman/listinfo/python-list
Class Variable Access and Assignment
This has to do with class variables and instances variables. Given the following: class _class: var = 0 #rest of the class instance_b = _class() _class.var=5 print instance_b.var # -> 5 print _class.var # -> 5 Initially this seems to make sense, note the difference between to last two lines, one is refering to the class variable 'var' via the class while the other refers to it via an instance. However if one attempts the following: instance_b.var = 1000 # -> _class.var = 5 _class.var = # -> _class.var = An obvious error occurs. When attempting to assign the class variable via the instance it instead creates a new entry in that instance's __dict__ and gives it the value. While this is allowed because of pythons ability to dynamically add attributes to a instance however it seems incorrect to have different behavior for different operations. There are two possible fixes, either by prohibiting instance variables with the same name as class variables, which would allow any reference to an instance of the class assign/read the value of the variable. Or to only allow class variables to be accessed via the class name itself. Many thanks to elpargo and coke. elpargo assisted in fleshing out the best way to present this. perhaps this was intended, i was just wondering if anyone else had noticed it, and if so what form would you consider to be 'proper' either referring to class variables via the class itself or via instances of that class. Any response would be greatly appreciated. Graham -- http://mail.python.org/mailman/listinfo/python-list
Class Variable Access and Assignment
This has to do with class variables and instances variables. Given the following: class _class: var = 0 #rest of the class instance_b = _class() _class.var=5 print instance_b.var # -> 5 print _class.var # -> 5 Initially this seems to make sense, note the difference between to last two lines, one is refering to the class variable 'var' via the class while the other refers to it via an instance. However if one attempts the following: instance_b.var = 1000 # -> _class.var = 5 _class.var = # -> _class.var = An obvious error occurs. When attempting to assign the class variable via the instance it instead creates a new entry in that instance's __dict__ and gives it the value. While this is allowed because of pythons ability to dynamically add attributes to a instance however it seems incorrect to have different behavior for different operations. There are two possible fixes, either by prohibiting instance variables with the same name as class variables, which would allow any reference to an instance of the class assign/read the value of the variable. Or to only allow class variables to be accessed via the class name itself. Many thanks to elpargo and coke. elpargo assisted in fleshing out the best way to present this. perhaps this was intended, i was just wondering if anyone else had noticed it, and if so what form would you consider to be 'proper' either referring to class variables via the class itself or via instances of that class. Any response would be greatly appreciated. Graham -- http://mail.python.org/mailman/listinfo/python-list
typo in the documentation or am I stupid?
In the embedding Python manual at Python.org an example is presented that uses the function: PyDict_GetAttrString. Is it possible that this is a typo? I have searched the source code and I can't find it, I have also used google and I only get 4 hits. In for example Programming Python another function with similar name is described: PyObject_GetAttrString. Could that be the one that fit into the example? Hopefully someone knows the answer to my question ;) //Tommy Link to the spot at Python.org: http://docs.python.org/ext/pure-embedding.html -- http://mail.python.org/mailman/listinfo/python-list
Re: Class Variable Access and Assignment
Graham wrote: > > > class _class: > var = 0 > #rest of the class > > instance_b = _class() > > _class.var=5 > > print instance_b.var # -> 5 > print _class.var # -> 5 > > > [...] > > > instance_b.var = 1000 # -> _class.var = 5 > _class.var = # -> _class.var = > > > > An obvious error occurs. Nope. 'var' is NOT a class variable! It is a pre-filled instance variable. You need some explicit programming to get class variables. --eric -- http://mail.python.org/mailman/listinfo/python-list
Unicode string and metakit database
I write a database application with Metakit. My script is like the
following:
...
vw = db.getas("t1[no:I,ch:S,code1:S,code2:S]")
...
*vw.append(no=i,ch=x,code1=y[0],code2=y[1])
...
But errors occured on "*" and it displayed "TypeError: not a Python
string".
x, y[0], y[1] are unicode strings. Doesn't Metakit support unicode or
else?
Thanks a lot!
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Re: Class Variable Access and Assignment
On Thu, 03 Nov 2005 01:43:32 -0800, Graham wrote: [snip] > print instance_b.var # -> 5 > print _class.var # -> 5 > > > > Initially this seems to make sense, note the difference between to last > two lines, one is refering to the class variable 'var' via the class > while the other refers to it via an instance. That's not correct. The line instance_b.var is referring to an instance attribute. According to the usual Object Oriented model of inheritance, if the instance does not have an attribute, the class is searched next. So instance_b.var and _class.var are asking for two different things. The first says, "Search the instance for attribute var, then the class." The second says "Search the class." BTW, a leading underscore is the convention for a private(ish) variable. The convention for naming a variable after a reserved word is a trailing underscore class_. In this case, there is also the convention that classes should start with a capital, so you have Class and instance. (instance, of course, is not a reserved word.) > However if one attempts the following: > > > > instance_b.var = 1000 # -> _class.var = 5 > _class.var = # -> _class.var = > > > > An obvious error occurs. I see no error. No exception is raised when I try it: I get the expected results. Assigning to an instance assigns to the instance, assigning to the class assigns to the class. That's normal OO behaviour. > When attempting to assign the class variable > via the instance it instead creates a new entry in that instance's > __dict__ and gives it the value. You might *want* to assign to the class attribute, but that's not what you are doing. You are assigning to the instance. Admittedly, it might not be the behaviour you expect, but it is the standard behaviour in (as far as I know) all OO languages. If you want to assign to the class attribute, you either assign to the class directly, or use instance_b.__class__.var. > While this is allowed because of > pythons ability to dynamically add attributes to a instance however it > seems incorrect to have different behavior for different operations. Surely you can't mean that? Why would you want different operations to have the same behaviour? > There are two possible fixes, either by prohibiting instance variables > with the same name as class variables, which would allow any reference > to an instance of the class assign/read the value of the variable. Or > to only allow class variables to be accessed via the class name itself. There is also a third fix: understand Python's OO model, especially inheritance, so that normal behaviour no longer surprises you. -- Steven. -- http://mail.python.org/mailman/listinfo/python-list
Re: Class Variable Access and Assignment
"Graham" <[EMAIL PROTECTED]> writes: > perhaps this was intended, i was just wondering if anyone else had > noticed it, and if so what form would you consider to be 'proper' > either referring to class variables via the class itself or via > instances of that class. Any response would be greatly appreciated. It was discussed before here and there's something about that at the docs: http://docs.python.org/tut/node11.html -- Jorge Godoy <[EMAIL PROTECTED]> -- http://mail.python.org/mailman/listinfo/python-list
strtok equvialent ?
Hi, are there a strtok equivalent in python ? str.split() only takes single seperator. -- http://mail.python.org/mailman/listinfo/python-list
Re: typo in the documentation or am I stupid?
[EMAIL PROTECTED] wrote_
> In the embedding Python manual at Python.org an example is presented
> that uses the function:
> PyDict_GetAttrString. Is it possible that this is a typo?
according to this checkin message ("fix stupid typo"), the answer is yes:
http://mail.python.org/pipermail/python-checkins/2005-October/047291.html
on the other hand, since the target is a module object, PyObject_GetAttrString
might be a better choice (no time to dig into this right now).
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Re: strtok equvialent ?
[EMAIL PROTECTED] wrote:
> are there a strtok equivalent in python ? str.split() only takes single
> seperator.
use a regular expression split with a character group:
>>> s = "breakfast=spam+egg-bacon"
>>> import re
>>> re.split("[-+=]", s)
['breakfast', 'spam', 'egg', 'bacon']
to deal with an arbitrary set of delimiting characters without having to
bother with RE syntax, use re.escape:
>>> re.split("[" + re.escape("-+=") + "]", s)
['breakfast', 'spam', 'egg', 'bacon']
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Anomaly in creating class methods
Hi, given below is my interaction with the interpreter In one case, i have created the class method using the "famous idiom"... and in the other, i have tried to create it outside the class definition... why isn't the latter working ? (of course, the presence of decorators is a different issue) >>> class D: ... def f(cls): ... print cls ... >>> D.f=classmethod(D.f) >>> D.f > >>> D.f() Traceback (most recent call last): File "", line 1, in ? TypeError: unbound method f() must be called with D instance as first argument (got classobj instance instead) >>> class D: ... def f(cls): ... print cls ... f=classmethod(f) ... >>> D.f > >>> D.f() __main__.D -- http://mail.python.org/mailman/listinfo/python-list
Re: strtok equvialent ?
thanks.
Fredrik Lundh wrote:
> [EMAIL PROTECTED] wrote:
>
> > are there a strtok equivalent in python ? str.split() only takes single
> > seperator.
>
> use a regular expression split with a character group:
>
> >>> s = "breakfast=spam+egg-bacon"
> >>> import re
> >>> re.split("[-+=]", s)
> ['breakfast', 'spam', 'egg', 'bacon']
>
> to deal with an arbitrary set of delimiting characters without having to
> bother with RE syntax, use re.escape:
>
> >>> re.split("[" + re.escape("-+=") + "]", s)
> ['breakfast', 'spam', 'egg', 'bacon']
>
>
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shared library search path
Hi. I've wrapped a C++ class with Boost.Python and that works great. But, I am now packaging my application so that it can be distributed. The structure is basically this: .../bin/foo.py .../lib/foo.so .../lib/bar.py In foo.py I do the following: sys.path.append(os.path.dirname(sys.path[0]) + '/lib') and this allows foo.py to import bar. Great. But, the foo.so cannot be imported. The import only succeeds if I place foo.so next to foo.py in the bin directory. I searched through the 2.4.2 documentation on python.org but I can't find a proper explanation on how the shared library loader works. Does anyone understand what it going on here? S. -- http://mail.python.org/mailman/listinfo/python-list
problem with async_chat
Hi there,
I am writing an application that requires a client-server interaction.
Looking up on the internet and working on it I came up with something
like this:
a class ADFSServer that takes inbound connections and dispatches them
to ADFSReceiver.
The connection is always initialized by ADFSSender.
here is the code:
import asynchat
import asyncore
import socket
import string
class ADFSServer (asyncore.dispatcher):
def __init__ (self, port):
asyncore.dispatcher.__init__ (self)
self.create_socket (socket.AF_INET, socket.SOCK_STREAM)
self.set_reuse_addr()
here = ('', port)
self.bind (here)
self.listen (1)
def handle_accept (self):
print ("Server is accepting connection")
ADFSReceiver (self, self.accept())
class ADFSReceiver (asynchat.async_chat):
channel_counter = 0
def __init__ (self, server, (conn, addr)):
asynchat.async_chat.__init__ (self, conn)
self.set_terminator ('\n')
self.server = server
self.id = self.channel_counter
self.channel_counter = self.channel_counter + 1
self.buffer = ''
print ("Receiver created")
def collect_incoming_data (self, data):
self.buffer.append(data)
print ("collecting data")
def found_terminator (self):
data = self.buffer
self.buffer = ''
print '[Received Message]\n %s' % (self.id, repr(data))
self.close()
return data
def handle_close (self):
print 'Closing receiver'
self.close()
class ADFSSender (asynchat.async_chat):
def __init__ (self, data, address):
print "creating sender"
asynchat.async_chat.__init__ (self)
#self.set_terminator ("\n")
self.create_socket (socket.AF_INET, socket.SOCK_STREAM)
self.connect (address)
self.push(data)
self.push ("\n")
if __name__ == '__main__':
work1 = ADFSServer (1234)
asyncore.loop()
I start the server on a shell, and from another shell I launch the
ADFSSender.
The problem is that if I use the push() function the code doesn't work.
If I use the send() it works.
As I am using the async_chat class, I would like to use the push()
method, so I was wondering what was the problem with my code...
thanks,
rix
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NTFS reparse points
I want to create a reparse point on NTFS (any). Here (http://msdn.microsoft.com/library/default.asp?url=/library/en-us/fileio/fs/reparse_points.asp) I read: "reparse points are used to implement NTFS file system links". Here (http://msdn.microsoft.com/library/default.asp?url=/library/en-us/fileio/fs/hard_links_and_junctions.asp) I read: "Soft links are implemented through reparse points". However I can't see FILE_ATTRIBUTE_REPARSE_POINT turned on in any file / directory shortcuts I create. In fact the only attribute set in shortcuts created using Windows Explorer is FILE_ATTRIBUTE_ARCHIVE. (I am using GetFileAttributes() to examine this.) The questions are: (1) Why is that so? (2) Does anybody have any idea (sample code?) on how to create a reparse point (the simpler, the better) using Python? I am using Windows 2000 Professional, Python 2.4 and Mark Hammond's Python for Windows Extensions build 204. Thank you. +---+ | When replying, please replace "my_initials" in the| | From: address field with my initials - that is, "SF". | +---+ -- http://www.nglogic.com Enter through the narrow gate! (Mt 7:13-14) -- http://mail.python.org/mailman/listinfo/python-list
Re: Python's website does a great disservice to the language
Alex Martelli wrote: > The Eternal Squire <[EMAIL PROTECTED]> wrote: >... > >>2) Consider what he really wants for a supervisor of software >>engineers. Ideally such a person should be a software engineer with >>at least 3 times the experience of the most junior member. Such a > > > I like the general idea but not your formula. If the most junior team > member was 1 month out of school, would it really be OK for the > supervisor to be somebody who graduated 3 months ago?-) > It worked for Microsoft ... regards Steve -- Steve Holden +44 150 684 7255 +1 800 494 3119 Holden Web LLC www.holdenweb.com PyCon TX 2006 www.python.org/pycon/ -- http://mail.python.org/mailman/listinfo/python-list
How to read all files in a directory
Dear All, My python application is small. It reads data from a file. My code is: fileName = '900128.DAT' dataFile = open(fileName, 'r').readlines() I have to run 100 input files .DAT. Each time I run application, I have to change code fileName to a new one. For example, fileName = 'NewFile.DAT'. I do not know how I can process all file with extension .DAT in a specific directory once only. Any suggestion will be appreciated, Thank you. -- http://mail.python.org/mailman/listinfo/python-list
Re: Class Variable Access and Assignment
Op 2005-11-03, Steven D'Aprano schreef <[EMAIL PROTECTED]>: >> There are two possible fixes, either by prohibiting instance variables >> with the same name as class variables, which would allow any reference >> to an instance of the class assign/read the value of the variable. Or >> to only allow class variables to be accessed via the class name itself. > > There is also a third fix: understand Python's OO model, especially > inheritance, so that normal behaviour no longer surprises you. No matter wat the OO model is, I don't think the following code exhibits sane behaviour: class A: a = 1 b = A() b.a += 2 print b.a print A.a Which results in 3 1 -- Antoon Pardon -- http://mail.python.org/mailman/listinfo/python-list
Re: How to read all files in a directory
"hungbichvo" <[EMAIL PROTECTED]> writes:
> Dear All,
>
> My python application is small. It reads data from a file.
> My code is:
>fileName = '900128.DAT'
>dataFile = open(fileName, 'r').readlines()
> I have to run 100 input files .DAT. Each time I run application, I have
> to change code fileName to a new one. For example, fileName
> = 'NewFile.DAT'.
> I do not know how I can process all file with extension .DAT in a
> specific directory once only.
>
> Any suggestion will be appreciated,
>
> Thank you.
http://www.python.org/doc/2.4.2/lib/module-glob.html
% python
Python 2.4.2 (#2, Sep 30 2005, 21:19:01)
[GCC 4.0.2 20050808 (prerelease) (Ubuntu 4.0.1-4ubuntu8)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import glob
>>> print glob.glob('*.rb')
['hello.rb', 'test.rb', 'ping.rb', 'echo.rb']
Sorry for the ruby code in the example :-)
S.
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Re: Class Variable Access and Assignment
Antoon Pardon <[EMAIL PROTECTED]> writes: > Op 2005-11-03, Steven D'Aprano schreef <[EMAIL PROTECTED]>: > > >> There are two possible fixes, either by prohibiting instance variables > >> with the same name as class variables, which would allow any reference > >> to an instance of the class assign/read the value of the variable. Or > >> to only allow class variables to be accessed via the class name itself. > > > > There is also a third fix: understand Python's OO model, especially > > inheritance, so that normal behaviour no longer surprises you. > > No matter wat the OO model is, I don't think the following code > exhibits sane behaviour: > > class A: > a = 1 > > b = A() > b.a += 2 > print b.a > print A.a > > Which results in > > 3 > 1 I find it confusing at first, but I do understand what happens :-) But really, what should be done different here? S. -- http://mail.python.org/mailman/listinfo/python-list
Getting Python Accepted in my Organisation
Hi Everyone, I'm working hard trying to get Python 'accepted' in the organisation I work for. I'm making some good in-roads. One chap sent me the text below on his views of Python. I wondered if anyone from the group could give me some advice on how to respond / if they had been in a similar position. Any help appreciated, Thanks in advance, - Stuart "Python is a scripting language like Perl, awk, tcl, Java etc... it is not quite a fully developed OO language, but does support some OO that Perl doesn't. To be clear, these scripting languages have their place in our environment, but they are not full replacements for C#, Java, C, etc... because they do not come with the full range of libraries e.g GDI libraries. Python has to be compared to Perl, Awk in order to evaluate it. Perl, until recently, did not support threading. Why would it? it is a scripting language and can run async shell commands. I would be interested to learn if Python supports a robust threading model (not just a pointer reference to an object), as this is a significant drawback when using a scripting language. CGI only works because the container can thread with Perl. Python is object orientated, but I do not know what implementation? Essentially any language with a pointer can claim to be OO, although Python does market itself on OO capabilities. Do you know what implementation they have used? Lets discuss, as I am not a great fan of Perl and if Python is more structured then it is possibly worth promoting." -- http://mail.python.org/mailman/listinfo/python-list
Re: Getting Python Accepted in my Organisation
Stuart Turner <[EMAIL PROTECTED]> writes: > Hi Everyone, > > I'm working hard trying to get Python 'accepted' in the organisation I work > for. I'm making some good in-roads. One chap sent me the text below on > his views of Python. I wondered if anyone from the group could give me > some advice on how to respond / if they had been in a similar position. What do you want to use Python for? What do you use now? S. -- http://mail.python.org/mailman/listinfo/python-list
Re: Getting Python Accepted in my Organisation
I'm already using it for a ton of things - I want to try and get broader acceptance in the organisation for it to be made and 'officially supported product'. Stefan Arentz wrote: > Stuart Turner <[EMAIL PROTECTED]> writes: > >> Hi Everyone, >> >> I'm working hard trying to get Python 'accepted' in the organisation I >> work >> for. I'm making some good in-roads. One chap sent me the text below on >> his views of Python. I wondered if anyone from the group could give me >> some advice on how to respond / if they had been in a similar position. > > What do you want to use Python for? What do you use now? > > S. -- http://mail.python.org/mailman/listinfo/python-list
Re: Class Variable Access and Assignment
Antoon Pardon wrote: > Op 2005-11-03, Steven D'Aprano schreef <[EMAIL PROTECTED]>: > > >>>There are two possible fixes, either by prohibiting instance variables >>>with the same name as class variables, which would allow any reference >>>to an instance of the class assign/read the value of the variable. Or >>>to only allow class variables to be accessed via the class name itself. >> >>There is also a third fix: understand Python's OO model, especially >>inheritance, so that normal behaviour no longer surprises you. > > > No matter wat the OO model is, I don't think the following code > exhibits sane behaviour: > > class A: > a = 1 > > b = A() > b.a += 2 > print b.a > print A.a > > Which results in > > 3 > 1 > I don't suppose you'd care to enlighten us on what you'd regard as the superior outcome? regards Steve -- Steve Holden +44 150 684 7255 +1 800 494 3119 Holden Web LLC www.holdenweb.com PyCon TX 2006 www.python.org/pycon/ -- http://mail.python.org/mailman/listinfo/python-list
Re: Getting Python Accepted in my Organisation
Stuart Turner <[EMAIL PROTECTED]> writes: > I'm already using it for a ton of things - I want to try and get broader > acceptance in the organisation for it to be made and 'officially supported > product'. IMO that is what you need to communicate: 'already using it for a ton of things' and probably adding 'being more productive than with tool XYZ' S. -- http://mail.python.org/mailman/listinfo/python-list
Re: OT - Re: Microsoft Hatred FAQ
On Thu, 03 Nov 2005 04:34:20 -0500, Tim Daneliuk wrote: > A) I don't much care if people wander off topic from time to time - > that's what filters are for. But as a matter of general courtesy > is it too much to ask that the subject line be so marked? Fair enough. > B) Rhetoric is not Reality. "Crime" has a very specific definition. > It always has one or more of Fraud, Force, or Threat. Nonsense. Jaywalking is a crime. So is littering. So is merely belonging to certain organisations, such as the German Nazi party or any number of allegedly terrorist groups. Walking around naked in public is a crime, and in many places in the world, including the USA, you then become a "registered sex offender" for the rest of your life. (So much for doing time and wiping the slate clean.) Possession of many substances is a crime in the USA, and not just drugs of addiction. There is no Fraud, Force or Threat involved in growing cannabis in your backyard, or selling pornography to teenagers, or driving without a licence. Possession of banned books is a crime in many countries, and yes even in the 21st century there are many, many banned books. If legislation being urged on the US Senate by the MPAA is passed, manufacturing, selling and possibly even possession of analog to digital devices will become a crime -- not just a civil offense, or a misdemeanor, but a felony. Even *accidents* can be crimes, if the circumstances are right (or perhaps I should say wrong). The act of manslaughter is still a crime, even if it does not include Fraud, Force or Threat. "Failing to do you job" can land you in jail, if people die because of your negligence. > No such > case against Microsoft has ever been levied. That is, if you ignore all the dozens of times Microsoft has either settled out of court or been found guilty of crimes by juries. > Just because *you* > don't like market outcomes doesn't make it a "crime". In civilizations that believe in freedom for human beings, freedom is not unlimited. There are actions which remain forbidden, even though that limits individual freedom. Bill Gates is not permitted to lock you up against your will: his freedom to restrict others' freedoms is severely curtailed. In civilizations that believe in free markets, freedom is also not unlimited. There are actions which are forbidden, because those actions restrict the freedom of others. Microsoft has been found guilty of deliberately committing those illegal acts, in Japan, Europe and even the USA. Just as Bill Gates can't legally hire henchmen to drag you away and lock you up in his basement, so he can't legally use economic punishment against anyone who would buy your goods or services, and for the same reason: his actions will infringe your freedoms. Those who believe in free markets understand that unrestricted freedom leads to the biggest bully limiting the freedoms of others. But then there are those that defend the right of bullies to limit the freedom of others. > C) Hate Microsoft all you want. But those of us old enough to have > actually done this for than 10 minutes recall the days where every single > hardware vendor was also a unique software and systems vendor. > Absent a Microsoft/Intel-style de facto standard, you'd never have > seen the ascent of Linux or Open Source as it exists today. Nonsense again. Real standards, like TCP/IP which is the backbone of the Internet, aren't controlled by any one company. Anyone can create a TCP stack. Nobody but Microsoft can create a competing version of Windows. TCP/IP became a standard long before Microsoft even acknowledged it's existence. So did ASCII, the IBM BIOS, and serial ports, to name just a few. Does the term "ISO standard" mean anything to you? Intel-compatible hardware is a true de facto standard, because there are actual competitors to Intel who product compatible but different hardware. AMD CPUs are different from Intel, but you can run the same copy of Windows on either and get the same results. The same can't be said of the Windows "standard" -- there is Microsoft Windows, and there is nothing else. While OS X or Linux or Solaris might do much the same sort of things as Windows, they aren't Windows-compatible in the same way that AMD and Intel CPUs are compatible. At best they can interoperate with Windows, or share data with Windows. You do your argument no favours by trying to confabulate the Microsoft monopoly in software with Intel's lack of monopoly. Intel has to compete in a free market, and hardware costs have fallen hugely: my first PC cost me AUD$4000 in 1986. Today I can get a machine a thousand times more powerful for $800. The first time I bought Microsoft Word and Excel, I paid around $100 each for them. MS Office retails at over $800 today, and you get very little extra functionality that didn't exist in 1986, lots more meaningless bells and whistles, and no printed documentation. In the same time that h
Re: OT - Re: Microsoft Hatred FAQ
Steven D'Aprano wrote: > Jaywalking is a crime. So is littering. So is merely belonging to certain > organisations, such as the German Nazi party or any number of allegedly > terrorist groups. Walking around naked in public is a crime, and in many > places in the world, including the USA, you then become a "registered sex > offender" for the rest of your life. (So much for doing time and wiping > the slate clean.) > > Possession of many substances is a crime in the USA, and not just drugs > of addiction. There is no Fraud, Force or Threat involved in growing > cannabis in your backyard, or selling pornography to teenagers, or driving > without a licence. > > Possession of banned books is a crime in many countries, [enough ...] Now, tell me: is the polluting of a newsgroup with off-topic postings, a crime, and if yes then what? Jerzy Karczmarczuk -- http://mail.python.org/mailman/listinfo/python-list
Re: Class Variable Access and Assignment
Op 2005-11-03, Stefan Arentz schreef <[EMAIL PROTECTED]>: > Antoon Pardon <[EMAIL PROTECTED]> writes: > >> Op 2005-11-03, Steven D'Aprano schreef <[EMAIL PROTECTED]>: >> >> >> There are two possible fixes, either by prohibiting instance variables >> >> with the same name as class variables, which would allow any reference >> >> to an instance of the class assign/read the value of the variable. Or >> >> to only allow class variables to be accessed via the class name itself. >> > >> > There is also a third fix: understand Python's OO model, especially >> > inheritance, so that normal behaviour no longer surprises you. >> >> No matter wat the OO model is, I don't think the following code >> exhibits sane behaviour: >> >> class A: >> a = 1 >> >> b = A() >> b.a += 2 >> print b.a >> print A.a >> >> Which results in >> >> 3 >> 1 > > I find it confusing at first, but I do understand what happens :-) I understand what happens too, that doesn't make it sane behaviour. > But really, what should be done different here? I don't care what should be different. But a line with only one referent to an object in it, shouldn't be referring to two different objects. In the line: b.a += 2, the b.a should be refering to the class variable or the object variable but not both. So either it could raise an attribute error or add two to the class variable. Sure one could object to those sematics too, but IMO they are preferable to what we have now. -- Antoon Pardon -- http://mail.python.org/mailman/listinfo/python-list
Re: Class Variable Access and Assignment
Steve Holden <[EMAIL PROTECTED]> writes: > > class A: > > a = 1 > > b = A() > > b.a += 2 > > print b.a > > print A.a > > Which results in > > 3 > > 1 > > > I don't suppose you'd care to enlighten us on what you'd regard as the > superior outcome? class A: a = [] b = A() b.append(3) print b.a print a.a Compare and contrast. -- http://mail.python.org/mailman/listinfo/python-list
Re: Class Variable Access and Assignment
On Thu, 03 Nov 2005 11:55:06 +, Antoon Pardon wrote: > No matter wat the OO model is, I don't think the following code > exhibits sane behaviour: > > class A: > a = 1 > > b = A() > b.a += 2 > print b.a > print A.a > > Which results in > > 3 > 1 Seems perfectly sane to me. What would you expect to get if you wrote b.a = b.a + 2? Why do you expect b.a += 2 to give a different result? Since ints are immutable objects, you shouldn't expect the value of b.a to be modified in place, and so there is an assignment to b.a, not A.a. On the other hand, if this happened: py> class A: ... a = [] ... py> b = A() py> b.a.append(None) py> print b.a, A.a [None], [] *then* you should be surprised. (Note that this is not what happens: you get [None], [None] as expected. The difference is that append modifies the mutable list in place.) -- Steven. -- http://mail.python.org/mailman/listinfo/python-list
wxGlade will not run on my machine
I have installed wxGlade on a MS XP machine. It executed on completion of the install. However, when I try to double click on the wxGlade icon to start nothing happens. I searched the NG and found that this had been report before but no solution was posted. I am running the following versions; Python 2.4.1 wxPython 2.6.1.0 Would like to give wxGlade a try. Len Sumnler -- http://mail.python.org/mailman/listinfo/python-list
Re: Class Variable Access and Assignment
Antoon Pardon <[EMAIL PROTECTED]> writes: ... > >> No matter wat the OO model is, I don't think the following code > >> exhibits sane behaviour: > >> > >> class A: > >> a = 1 > >> > >> b = A() > >> b.a += 2 > >> print b.a > >> print A.a > >> > >> Which results in > >> > >> 3 > >> 1 > > > > I find it confusing at first, but I do understand what happens :-) > > I understand what happens too, that doesn't make it sane behaviour. > > > But really, what should be done different here? > > I don't care what should be different. But a line with only one > referent to an object in it, shouldn't be referring to two different > objects. It doesn't. > In the line: b.a += 2, the b.a should be refering to the class variable > or the object variable but not both. So either it could raise an > attribute error or add two to the class variable. It does exactly what you say. It adds 2 to the a *instance variable* of the object instance in 'b'. It doesn't touch the *class variable* A.a which is still 1. S. -- http://mail.python.org/mailman/listinfo/python-list
Release of PyPy 0.8.0
pypy-0.8.0: Translatable compiler/parser and some more speed == The PyPy development team has been busy working and we've now packaged our latest improvements, completed work and new experiments as version 0.8.0, our third public release. The highlights of this third release of PyPy are: - Translatable parser and AST compiler. PyPy now integrates its own compiler based on Python own 'compiler' package but with a number of fixes and code simplifications in order to get it translated with the rest of PyPy. This makes using the translated pypy interactively much more pleasant, as compilation is considerably faster than in 0.7.0. - Some Speed enhancements. Translated PyPy is now about 10 times faster than 0.7 but still 10-20 times slower than CPython on pystones and other benchmarks. At the same time, language compliancy has been slightly increased compared to 0.7 which had already reached major CPython compliancy goals. - Some experimental features are now translateable. Since 0.6.0, PyPy shipped with an experimental Object Space (the part of PyPy implementing Python object operations and manipulation) implementing lazily computed objects, the "Thunk" object space. With 0.8.0 this object space can also be translated preserving its feature additions. What is PyPy (about)? PyPy is a MIT-licensed research-oriented reimplementation of Python written in Python itself, flexible and easy to experiment with. It translates itself to lower level languages. Our goals are to target a large variety of platforms, small and large, by providing a compilation toolsuite that can produce custom Python versions. Platform, Memory and Threading models are to become aspects of the translation process - as opposed to encoding low level details into a language implementation itself. Eventually, dynamic optimization techniques - implemented as another translation aspect - should become robust against language changes. Note that PyPy is mainly a research and development project and does not by itself focus on getting a production-ready Python implementation although we do hope and expect it to become a viable contender in that area sometime next year. PyPy is partially funded as a research project under the European Union's IST programme. Where to start? - Getting started: http://codespeak.net/pypy/dist/pypy/doc/getting-started.html PyPy Documentation: http://codespeak.net/pypy/dist/pypy/doc/ PyPy Homepage: http://codespeak.net/pypy/ The interpreter and object model implementations shipped with the 0.8 version can run on their own and implement the core language features of Python as of CPython 2.4. However, we still do not recommend using PyPy for anything else than for education, playing or research purposes. Ongoing work and near term goals - At the last sprint in Paris we started exploring the new directions of our work, in terms of extending and optimising PyPy further. We started to scratch the surface of Just-In-Time compiler related work, which we still expect will be the major source of our future speed improvements and some successful amount of work has been done on the support needed for stackless-like features. This release also includes the snapshots in preliminary or embryonic form of the following interesting but yet not completed sub projects: - The OOtyper, a RTyper variation for higher-level backends (Squeak, ...) - A JavaScript backend - A limited (PPC) assembler backend (this related to the JIT) - some bits for a socket module PyPy has been developed during approximately 16 coding sprints across Europe and the US. It continues to be a very dynamically and incrementally evolving project with many of these one-week workshops to follow. PyPy has been a community effort from the start and it would not have got that far without the coding and feedback support from numerous people. Please feel free to give feedback and raise questions. contact points: http://codespeak.net/pypy/dist/pypy/doc/contact.html have fun, the pypy team, (Armin Rigo, Samuele Pedroni, Holger Krekel, Christian Tismer, Carl Friedrich Bolz, Michael Hudson, and many others: http://codespeak.net/pypy/dist/pypy/doc/contributor.html) PyPy development and activities happen as an open source project and with the support of a consortium partially funded by a two year European Union IST research grant. The full partners of that consortium are: Heinrich-Heine University (Germany), AB Strakt (Sweden) merlinux GmbH (Germany), tismerysoft GmbH (Germany) Logilab Paris (France), DFKI GmbH (Germany) ChangeMaker (Sweden), Impara (Germany) -- http://mail.python.org/mailman/listinfo/python-list
Re: how to write a blog system with Python
Thanks for all your comments. What I wanted is a chance to practise my programming talents with Python. -- http://mail.python.org/mailman/listinfo/python-list
Re: Class Variable Access and Assignment
Paul Rubin wrote: > Steve Holden <[EMAIL PROTECTED]> writes: > >>>class A: >>> a = 1 >>>b = A() >>>b.a += 2 >>>print b.a >>>print A.a >>>Which results in >>>3 >>>1 >>> >> >>I don't suppose you'd care to enlighten us on what you'd regard as the >>superior outcome? > > > class A: > a = [] > b = A() > b.append(3) > print b.a > print a.a > > Compare and contrast. append() guarantees to modify a mutable object in place. Augmented assignment operations don't,but are "normally" equivalent to name = name operator value In the former case exactly such semantics are implemented. I still don;t see anyone suggesting a better outcome for the augmented assignment. regards Steve -- Steve Holden +44 150 684 7255 +1 800 494 3119 Holden Web LLC www.holdenweb.com PyCon TX 2006 www.python.org/pycon/ -- http://mail.python.org/mailman/listinfo/python-list
Re: Class Variable Access and Assignment
Op 2005-11-03, Stefan Arentz schreef <[EMAIL PROTECTED]>: > Antoon Pardon <[EMAIL PROTECTED]> writes: > > ... > >> >> No matter wat the OO model is, I don't think the following code >> >> exhibits sane behaviour: >> >> >> >> class A: >> >> a = 1 >> >> >> >> b = A() >> >> b.a += 2 >> >> print b.a >> >> print A.a >> >> >> >> Which results in >> >> >> >> 3 >> >> 1 >> > >> > I find it confusing at first, but I do understand what happens :-) >> >> I understand what happens too, that doesn't make it sane behaviour. >> >> > But really, what should be done different here? >> >> I don't care what should be different. But a line with only one >> referent to an object in it, shouldn't be referring to two different >> objects. > > It doesn't. Yes it does. If the b.a refers to the instance variable, then an AttributeError should be raised, because the instance variable doesn't exist yet, so you can't add two to it. If the b.a refers to the class variable then two should be added to it. Neither happens instead we get some hybrid in which an instance varible is created that gets the value of class variable incrented by two. >> In the line: b.a += 2, the b.a should be refering to the class variable >> or the object variable but not both. So either it could raise an >> attribute error or add two to the class variable. > > It does exactly what you say. It adds 2 to the a *instance variable* of > the object instance in 'b'. There is no instance variable at that point. How can it add 2, to something that doesn't exist at the moment. > It doesn't touch the *class variable* A.a which is still 1. But it accesses the class variable. -- Antoon Pardon -- http://mail.python.org/mailman/listinfo/python-list
Re: Filepath string manipulation help
Thanks guys. The os.path method works, but this is for a script for a website upload program on a zope webserver. For some reason even admin access won't let me run the script through the server. The main issue with my script is that Firefox has no problem with the program the way it is, but IE somehow uses a different filename format. ex:/ In IE filepath='c:\documents\web\zope\file.ext' In Firefox filepath='file.ext' So when IE goes to upload the file, it gets an error for illegal characters because of the "\"'s and ":" Is there another way to do this (extract just the filename) using something else other than the "os" that won't be blocked by the webserver -- http://mail.python.org/mailman/listinfo/python-list
Re: [OT] Gmane/Tunderbird users: is g.c.p.general too big?
Robert Kern wrote: > Steve Holden wrote: > >>Sorry about this almost off-topic post, but I am guessing there must be >>other readers of this group who use Thunderbird (in my case 1.0.2) to >>access it as gmane.comp.general.python. >> >>I'm currently showing 344,548 articles in the group due to the gmane >>policy of permanent retention, and lately it seems to have started >>taking forever to switch from mailboxes to the newsgroup. Furthermore, >>the Thunderbird process's memory usage climbs from ~30MB reading mail to >>over 200MB reading the newsgroup. >> >>Has anyone else noticed this, or is it specific to my setup? Does anyone >>have a solution? > > > You can specify a policy for keeping old messages for each server > account. Go to your "Account Settings" for GMane and look in "Offline & > Disk Space". You can choose to keep all messages, the newest N messages, > or messages from the past N days. > Thanks, that's done it. A few days ago Thunderbird had a giddy fit and suddenly decided that every article on the server was unread. I don't know what happened, but after resetting the Thunderbird policy for the group (and waiting three minutes for it to comb through everything) all is well again. regards Steve -- Steve Holden +44 150 684 7255 +1 800 494 3119 Holden Web LLC www.holdenweb.com PyCon TX 2006 www.python.org/pycon/ -- http://mail.python.org/mailman/listinfo/python-list
Re: Class Variable Access and Assignment
Op 2005-11-03, Steven D'Aprano schreef <[EMAIL PROTECTED]>: > On Thu, 03 Nov 2005 11:55:06 +, Antoon Pardon wrote: > >> No matter wat the OO model is, I don't think the following code >> exhibits sane behaviour: >> >> class A: >> a = 1 >> >> b = A() >> b.a += 2 >> print b.a >> print A.a >> >> Which results in >> >> 3 >> 1 > > Seems perfectly sane to me. > > What would you expect to get if you wrote b.a = b.a + 2? I would expect a result consistent with the fact that both times b.a would refer to the same object. > Why do you expect > b.a += 2 to give a different result? I didn't know I did. > Since ints are immutable objects, you shouldn't expect the value of b.a > to be modified in place, and so there is an assignment to b.a, not A.a. You are now talking implementation details. I don't care about whatever explanation you give in terms of implementation details. I don't think it is sane that in a language multiple occurence of something like b.a in the same line can refer to different objects I think it even less sane, if the same occurce of b.a refers to two different objects, like in b.a += 2 -- Antoon Pardon. -- http://mail.python.org/mailman/listinfo/python-list
Re: XML DOM: XML/XHTML inside a text node
Roman Suzi wrote: > > On Thu, 2 Nov 2005 [EMAIL PROTECTED] wrote: > > Is there a better way? > > What about parsing the input into XML first? Is there any point in including > unescaped code into XML document unless it is XML itself? Indeed. My approach would be to parse the user's input using the parseString function, to get the "root element" of this newly parsed document, and then to import that element into the existing document using importNode. The imported document information could then be inserted into the existing document at a suitable place. For example: user_doc = xml.dom.minidom.parseString(user_input) # NOTE: Check for element or use XPath here... user_doc_root = user_doc.childNodes[0] imported_root = existing_doc.importNode(user_doc_root, 1) existing_doc_location.appendChild(imported_root) Paul -- http://mail.python.org/mailman/listinfo/python-list
Re: Getting Python Accepted in my Organisation
Stefan Arentz wrote: > Stuart Turner <[EMAIL PROTECTED]> writes: > > > I'm already using it for a ton of things - I want to try and get broader > > acceptance in the organisation for it to be made and 'officially supported > > product'. > > IMO that is what you need to communicate: 'already using it for a ton of > things' and probably adding 'being more productive than with tool XYZ' > > S. It didn't work well in my case. I still use Python for "tons of things" but it didn't change the attitudes of my co-workers towards learning a new language. It just changed my status as a programmer inside of the department. And remember: Python is still cutting edge as a language but sub-standard when it comes to tool support i.e. you do not have to introduce just a language but a different culture of programming as it is common sense now. Kay -- http://mail.python.org/mailman/listinfo/python-list
Re: Python for .NET and IronPython
I just want to clarify that the above mentioned web site (www.ironpython.com) is no longer maintained. If you want to get updated information on IronPython, you should visit this site: www.gotdotnet.com/Workspaces/Workspace. aspx?id=ad7acff7-ab1e-4bcb-99c0-57ac5a3a9742 Or the mailing list here: http://lists.ironpython.com/pipermail/users-ironpython.com/ By the way, the current version is 0.9.3 and it's advancing at a pretty fast pace towards version 1.0. Luis -- http://mail.python.org/mailman/listinfo/python-list
Re: Getting Python Accepted in my Organisation
Stuart Turner wrote: > Hi Everyone, > > I'm working hard trying to get Python 'accepted' in the organisation I work > for. I'm making some good in-roads. One chap sent me the text below on > his views of Python. I wondered if anyone from the group could give me > some advice on how to respond / if they had been in a similar position. > > Any help appreciated, > > Thanks in advance, > > - Stuart > > > "Python is a scripting language like Perl, awk, tcl, Java etc... it is > not quite a fully developed OO language, but does support some OO that Perl > doesn't. To be clear, these scripting languages have their place in our > environment, but they are not full replacements for C#, Java, C, etc... > because they do not come with the full range of libraries e.g GDI > libraries. Python has to be compared to Perl, Awk in order to evaluate it. > Perl, until recently, did not support threading. Why would it? it is a > scripting language and can run async shell commands. I would be interested > to learn if Python supports a robust threading model (not just a pointer > reference to an object), as this is a significant drawback when using a > scripting language. CGI only works because the container can thread with > Perl. Python is object orientated, but I do not know what implementation? > Essentially any language with a pointer can claim to be OO, although Python > does market itself on OO capabilities. Do you know what implementation > they have used? > > Lets discuss, as I am not a great fan of Perl and if Python is more > structured then it is possibly worth promoting." First of all, let's dismiss the notion that "Python is a scripting language". It can be used for scripting tasks, and has been successfully so used in many environments, but it's a fully-developed programming language with a well-defined and cleanly-implemented OO model. Many people call Python a scripting language because it is interpreted, but the parallel with Java is better that that with Perl, since Python compiles programs into bytecodes for a virtual machine. An advantage of Python is that while it is fully object-oriented it is also well-suited to procedural programming and, unlike Java, you are not forced to try and fit all tasks into an object-oriented model. Python does indeed support a robust threading model, and has recently improved threading support still further by adding explicit features to support per-thread state in a cleaner way. It has been used to implement many high-volume asynchronous network server tasks, among which Zope is perhaps the best known. The author of your comments asks "what implementation" of OO capabilities Python uses. This is a very broad question, but basically Python uses a multiple-inheritance model (though nobody is forced to use multiple superclasses) and has a very clean object orientation. For background I have been studying and working with object oriented languages for over thirty years, and find Python the most natural and cleanest way to express many object oriented programming solutions. Finally I feel that the Python community is much more welcoming than that of most programming languages, which is important if you are looking for support as your familiarity with the language grows. Good luck with your Python advocacy. regards Steve -- Steve Holden +44 150 684 7255 +1 800 494 3119 Holden Web LLC www.holdenweb.com PyCon TX 2006 www.python.org/pycon/ -- http://mail.python.org/mailman/listinfo/python-list
Re: Class Variable Access and Assignment
Op 2005-11-03, Steve Holden schreef <[EMAIL PROTECTED]>: > Antoon Pardon wrote: >> Op 2005-11-03, Steven D'Aprano schreef <[EMAIL PROTECTED]>: >> >> There are two possible fixes, either by prohibiting instance variables with the same name as class variables, which would allow any reference to an instance of the class assign/read the value of the variable. Or to only allow class variables to be accessed via the class name itself. >>> >>>There is also a third fix: understand Python's OO model, especially >>>inheritance, so that normal behaviour no longer surprises you. >> >> >> No matter wat the OO model is, I don't think the following code >> exhibits sane behaviour: >> >> class A: >> a = 1 >> >> b = A() >> b.a += 2 >> print b.a >> print A.a >> >> Which results in >> >> 3 >> 1 >> > I don't suppose you'd care to enlighten us on what you'd regard as the > superior outcome? No. I don't think a superior outcome is necessary to see that this is not sane behaviour. I don't care that much on how it gets fixed. -- Antoon Pardon -- http://mail.python.org/mailman/listinfo/python-list
__slots__ and class attributes
I'm running into a something unexpected for a new-style class that has both a class attribute and __slots__ defined. If the name of the class attribute also exists in __slots__, Python throws an AttributeError. Is this by design (if so, why)? class A( object ): __slots__ = ( 'value', ) value = 1 def __init__( self, value = None ): self.value = value or A.value a = A() print a.value Traceback (most recent call last): File "t1.py", line 8, in ? a = A() File "t1.py", line 6, in __init__ self.value = value or A.value AttributeError: 'A' object attribute 'value' is read-only -- http://mail.python.org/mailman/listinfo/python-list
Re: Class Variable Access and Assignment
Antoon Pardon enlightened us with: > I would expect a result consistent with the fact that both times b.a > would refer to the same object. "b.a" is just a name, not a pointer to a spot in memory. Getting the value associated with that name is something different from assigning a new value to that name. Sybren -- The problem with the world is stupidity. Not saying there should be a capital punishment for stupidity, but why don't we just take the safety labels off of everything and let the problem solve itself? Frank Zappa -- http://mail.python.org/mailman/listinfo/python-list
Re: Getting Python Accepted in my Organisation
How about, Google use python extensively ? This I believe is a very strong argument for any concern about python. However, policy in organisations can be very funny and many of them may be set long time ago which even though may no longer be relavent are still "policy". I would suggest focus on why the policy(like why distinguish between script vs compiled language, as the rationale behind it can be performance) and address it accordingly rather than taking literal arguments. Stuart Turner wrote: > Hi Everyone, > > I'm working hard trying to get Python 'accepted' in the organisation I work > for. I'm making some good in-roads. One chap sent me the text below on > his views of Python. I wondered if anyone from the group could give me > some advice on how to respond / if they had been in a similar position. > > Any help appreciated, > > Thanks in advance, > > - Stuart > > > "Python is a scripting language like Perl, awk, tcl, Java etc... it is > not quite a fully developed OO language, but does support some OO that Perl > doesn't. To be clear, these scripting languages have their place in our > environment, but they are not full replacements for C#, Java, C, etc... > because they do not come with the full range of libraries e.g GDI > libraries. Python has to be compared to Perl, Awk in order to evaluate it. > Perl, until recently, did not support threading. Why would it? it is a > scripting language and can run async shell commands. I would be interested > to learn if Python supports a robust threading model (not just a pointer > reference to an object), as this is a significant drawback when using a > scripting language. CGI only works because the container can thread with > Perl. Python is object orientated, but I do not know what implementation? > Essentially any language with a pointer can claim to be OO, although Python > does market itself on OO capabilities. Do you know what implementation > they have used? > > Lets discuss, as I am not a great fan of Perl and if Python is more > structured then it is possibly worth promoting." -- http://mail.python.org/mailman/listinfo/python-list
Re: Class Variable Access and Assignment
You see, The seen behavior is due to the result of python's name binding,scoping scheme. Let me give you an example, class A: i=0 def t(self): print self.i self.i=4 then a=A() a.i is 0 a.t() then, A.i is 0 a.i is 4 In the function, it first searches for i in its local scope, on not finding it, accesses the class object's i. then the next line, is an assignment, which binds (creates a new variable) in the instance's scope. you can use the buit-in id function to verify it. the same thing happens in the case of b.a = b.a + 2 search for b.a not found, read the value from the enclosing scope (of the class object) then assign b.a to the local scope, with the value 3. But, I think your question about the sanity of the behaviour should be analysed sincerely if, k=0 def f(): print k k=k+1 raises UnboundLocalError, then how is it accepted in the former case? hmmm maybe, my arguments are hapazard but, i'll get to know when i'm flamed ;) -- http://mail.python.org/mailman/listinfo/python-list
Re: Python for .NET and IronPython
John Salerno wrote:
> Hi all. I'm currently learning C#, and I'm also interested in learning
> Python
In a similar position to yourself - learning both languages - I can
definitely recommend Python ( though C# 's curly brackets might annoy
you more than they did before!!)
> so it seems like a decent
> idea to want to integrate the two
FWIW, what I've been doing lately is calling Python scripts from
Windows.Forms apps, capturing their 'StdOut'. There's an article on
http://www.thecodeproject.com which explains how you can do this
asynchronously, but the following (C#) code is what I'm using ( imagine
a Windows Form with a TextBox to enter the script name, another to
enter any arguments for the script, and 'Run', 'Cancel' and 'Browse'
CommandButtons).
(assumes the script requires no user interaction)
private void BrowseForScript_Click(object sender, System.EventArgs e)
{
if ( this.openFileDialog.ShowDialog() == DialogResult.OK )
{
this.txtIO.Clear();
this.txtIO.Focus();
this.txtIO.AppendText( openFileDialog.FileName);
}
}
private void Run_Click(object sender, System.EventArgs e)
{
System.Diagnostics.ProcessStartInfo startInfo;
System.Diagnostics.Process process;
string directory;
string pyArgs;
string script;
script = this.txtIO.Text.Trim();
if ( script == null || script.Length == 0 )
{
return;
}
try
{
directory = Path.GetDirectoryName( script );
script = Path.GetFileName( script );
}
catch (ArgumentException)
{
MessageBox.Show("The script file path contains invalid
characters.",
"Invalid Script Path",
MessageBoxButtons.OK,
MessageBoxIcon.Error);
return;
}
if ( script.Length == 0 )
{
MessageBox.Show("No script file has been specified.",
"Invalid Script Path",
MessageBoxButtons.OK,
MessageBoxIcon.Error);
return;
}
if ( directory == null || directory.Length == 0 )
{
directory = DEFAULT_SCRIPT_DIRECTORY;
}
pyArgs = this.txtArgs.Text.Trim();
startInfo = new ProcessStartInfo("python");
startInfo.WorkingDirectory = directory;
startInfo.Arguments = script + " " + pyArgs;
startInfo.UseShellExecute = false;
startInfo.CreateNoWindow = true;
startInfo.RedirectStandardOutput = true;
startInfo.RedirectStandardError = true;
process = new Process();
process.StartInfo = startInfo;
process.Start();
string s;
while ((s = process.StandardOutput.ReadLine()) != null)
{
this.__application.Write( s + "\n" );
}
while ((s = process.StandardError.ReadLine()) != null)
{
this.__application.Write( s + "\n" );
}
}
Gerard
--
http://mail.python.org/mailman/listinfo/python-list
Re: Class Variable Access and Assignment
Op 2005-11-03, venk schreef <[EMAIL PROTECTED]>: > You see, > The seen behavior is due to the result of python's name > binding,scoping scheme. I know what causes the behaviour. But I still think it is not sane behaviour. > ... > > the same thing happens in the case of b.a = b.a + 2 search for b.a > not found, read the value from the enclosing scope (of the class > object) then assign b.a to the local scope, with the value 3. This is an explanation depending on a specific implementation. Now can you give me a language design argument that supports the idea that in "b.a = b.a + 2" b.a refers to two different objects. And even if you could do that, can you give such an argument that in "b.a += 2" that one occurence of b.a should refer to two different objects. Suppose I have code like this: for i in xrange(1,11): b.a = b.a + i Now the b.a on the right hand side refers to A.a the first time through the loop but not the next times. I don't think it is sane that which object is refered to depends on how many times you already went through the loop. -- Antoon Pardon -- http://mail.python.org/mailman/listinfo/python-list
installing PygreSQL and psychopg2 modules (a newbie question)
Hello.
I was trying to install PygreSQL and psychopg2 in
order to use python as front-end for PostgreSQL, on WIndows XP.
When I tried to install by calling setup.py from
command prompt ("setup.py install"), in both cases I had the same
error:
"error: Python was built with version 7.1 of Visual
Studio, and extensions need to be built with the same version of the compiler,
but it isn't installed."
It looks like
this:"C:\Downloads\Python\psychopg\psycopg2-2.0b5\psycopg2-2.0b5>setup.py
installrunning installrunning buildrunning build_pyrunning
build_extbuilding 'psycopg2._psycopg' extensionerror: Python was built
with version 7.1 of Visual Studio, and extensions need to be built with
the same version of the compiler, but it isn't
installed.C:\Downloads\Python\psychopg\psycopg2-2.0b5\psycopg2-2.0b5>pausePress
any key to continue . . ."
What does it mean ? What am I supposed to
do?
Thanks,
Zlatko
--
http://mail.python.org/mailman/listinfo/python-list
Re: Class Variable Access and Assignment
Op 2005-11-03, Sybren Stuvel schreef <[EMAIL PROTECTED]>: > Antoon Pardon enlightened us with: >> I would expect a result consistent with the fact that both times b.a >> would refer to the same object. > > "b.a" is just a name, not a pointer to a spot in memory. Getting the > value associated with that name is something different from assigning > a new value to that name. If that was all to it, one would expect the following to work to: >>> a = 1 >>> def f(): ... a += 2 ... >>> f() Traceback (most recent call last): File "", line 1, in ? File "", line 2, in f UnboundLocalError: local variable 'a' referenced before assignment But I'll word it differently: I would expect a result consistent with the fact that both times b.a would be resolved in the same name space. -- http://mail.python.org/mailman/listinfo/python-list
Re: OT - Re: Microsoft Hatred FAQ
Hi, Though out of the streamline, I find your post to be one of the most reasonable and well-formed arguments I have read in a long time. Keep it up. Great work. Steven D'Aprano wrote: Real standards, like TCP/IP which is the backbone of the Internet, aren't controlled by any one company. Anyone can create a TCP stack. Nobody but Microsoft can create a competing version of Windows. TCP/IP became a standard long before Microsoft even acknowledged it's existence. So did ASCII, the IBM BIOS, and serial ports, to name just a few. Does the term "ISO standard" mean anything to you? -- http://mail.python.org/mailman/listinfo/python-list
Re: Class Variable Access and Assignment
Antoon Pardon <[EMAIL PROTECTED]> writes: > Op 2005-11-03, venk schreef <[EMAIL PROTECTED]>: > > You see, > > The seen behavior is due to the result of python's name > > binding,scoping scheme. > > I know what causes the behaviour. But I still think it is > not sane behaviour. > > > > ... > > > > the same thing happens in the case of b.a = b.a + 2 search for b.a > > not found, read the value from the enclosing scope (of the class > > object) then assign b.a to the local scope, with the value 3. > > This is an explanation depending on a specific implementation. > > Now can you give me a language design argument that supports the > idea that in "b.a = b.a + 2" b.a refers to two different objects. > > And even if you could do that, can you give such an argument that > in "b.a += 2" that one occurence of b.a should refer to two different > objects. Your problem is a namespace conflict together with a certain stubborness about lookup order :-) It is really simple. When you say b.a then the instance variable 'a' is looked up first. If it does not exist then a class variable lookup is done. Remember, Python is a dynamic language. It is all according to how things have been in Python for a long time. The real issue here is that you should propery name class variables so that there can't be any confusion about class or instance scope. I use all uppercase identifiers for class variables for example. S. -- http://mail.python.org/mailman/listinfo/python-list
Re: Most efficient way of storing 1024*1024 bits
On 3 Nov 2005, at 05:03, Alex Martelli wrote: > Brandon K <[EMAIL PROTECTED]> wrote [inverting his topposting!]: > > >>> Six megabytes is pretty much nothing on a modern computer. >>> > > >> BTW, it'd be 6 megabits or 750kb ;) >> > > ...but Mike was proposing using one digit per bit, hence, 6 megabytes. > That makes it easy to search for bitpatterns with re or > string.find; if > the bits were packed 8 to a byte, such searches would be very hard. > They would just require some out-of-the-box thinking using character arrays and stuff I think. It's definately still doable with regex's if you really want to. -- http://mail.python.org/mailman/listinfo/python-list
Re: Class Variable Access and Assignment
hey, did u read my reply fully? i too feel that this matter of raising unbound local error in one case and not raising it in the other must be analysed... quoting from the documentation "If a name binding operation occurs anywhere within a code block, all uses of the name within the block are treated as references to the current block. This can lead to errors when a name is used within a block before it is bound. This rule is subtle. Python lacks declarations and allows name binding operations to occur anywhere within a code block. The local variables of a code block can be determined by scanning the entire text of the block for name binding operations." -- http://mail.python.org/mailman/listinfo/python-list
Re: Getting Python Accepted in my Organisation
Stuart Turner <[EMAIL PROTECTED]> wrote: > "Python is a scripting language like Perl, awk, tcl, Java etc... It is difficult to say whether Python is a scripting language or not until you define what you mean by "scripting language". People throw the term "scripting language" around with wild abandon these days. As far as I can tell, what they usually mean is something like, "It's not C++", or perhaps somewhat more generally, "It doesn't fit the compile-link-load-execute model I learned in college 20 years ago". > it is not quite a fully developed OO language Ask the guy in what way he thinks it's not quite fully developed. My guess is he doesn't really know, or perhaps will latch onto something like "it doesn't have private data". That is true, but only partially so. And for people who are hung up on that, you can point out that it's also only partially true about C++. Some people have been working with C++ and Java for so long they have started to think that "OO" means "The way C++ and Java do things", which pretty much means static typing and complex access control models. It doesn't have to be that way. > To be clear, these scripting languages have their place in our > environment, but they are not full replacements for C#, Java, C, etc... With this I am in complete agreement. A good craftsman keeps a wide selection of tools at his or her disposal. Each is useful for some tasks, can be pressed into service for many more, and is utterly wrong for others. > because they do not come with the full range of libraries e.g GDI > libraries. No language has libraries for everything you might ever possibly want to do. Python has a wide range of libraries for many common tasks, but my no means all. Still, if it comes down to "language X has a good library for what we need and language Y doesn't", that will often be (and rightly so) the decision maker as to which language to use. > Python has to be compared to Perl, Awk in order to evaluate it. Comparing Python to Perl makes a lot of sense, but comparing it to Awk is absurd. What Awk provides is decent flow control (including an implicit read-match-execute outer loop), excellent pattern matching, automatic memory management, implicit string-numeric conversion, and associative arrays. Packaging all this up in a handy to use form was a great advance, and the features it provides are well suited for a large class of data reduction and text processing tasks. But, Awk has no OO features, is not extensible, has poor error handling, and provides no system access. It doesn't even have subroutines. It is, with some minor exceptions, a "read one input stream, process it in a single pass, write one output stream" text processing scripting (there's that word again) language. If you want to compare Python to other roughly similar languages, I would include Perl, Java, Tcl, and Ruby. If this guy thinks comparing Python to Awk makes sense, he either has no clue what Awk is, or no clue what Python is. BTW, comparing Java, Tcl, or Ruby to Awk would be equally absurd. > Essentially any language with a pointer can claim to be OO, And Perl is the proof of that statement! -- http://mail.python.org/mailman/listinfo/python-list
Re: Class Variable Access and Assignment
Stefan Arentz wrote: > It is really simple. When you say b.a then the instance variable 'a' > is looked up first. If it does not exist then a class variable lookup > is done. This mixing of class and instance variable might be the cause of confusion... I think of it as follows: 1 When the class statement ends a class object is created which is filled by all the statements inside the class statement This means all variables and functions (methods) are created according to the description. NOTE This happens just once. 2 When an instance of the class is created, what effectively happens is that a shallow copy of the class object is made. Simple values and object references are copied. This explains: - why methods and complex objects (e.g. lists) are shared among instances of a class and the class itself - simple values are not shared --eric -- http://mail.python.org/mailman/listinfo/python-list
sizers in boa constructors
hi, I am trying to build a small gui program in python using boa constructor. i have a few problems. i would be grateful if anyone can help me in this regard. 1. i have four static text controls positioned one below the other. what i want to do is when i change the content of the upper static text control, the lower ones should reposition themselves, with a constant seperation, say 25px from the upper ones. I am not able to do this. when i change the label of upper static text, the text overlaps on the lower ones. 2. i am not able to implement sizers in general using boa. if anyone can suggest some resources where i can get information, i would be grateful thanks -- http://mail.python.org/mailman/listinfo/python-list
Re: Python and MySQL
Aquarius <[EMAIL PROTECTED]> wrote: >I want to know if there is a way to interface a MySQL database without >Python-MySQL or without installing anything that has C files that need >to be compiled. The reason for this, is that I want to develop a >certain web application, but my hosting provider ([EMAIL PROTECTED]@#%) isn't >very >eager to supply Python-MySQL (or any modules to python). Is there an >alternative approach I could use to pass around this ridiculos lack of >functionality? If you've got MySQL installed, you probably have a command-line mysql client, and you could use subprocess or popen to run that. That's a little desperate though, and the error handling will suck. (I've seen this trick used with other databases.) -- \S -- [EMAIL PROTECTED] -- http://www.chaos.org.uk/~sion/ ___ | "Frankly I have no feelings towards penguins one way or the other" \X/ |-- Arthur C. Clarke her nu becomeþ se bera eadward ofdun hlæddre heafdes bæce bump bump bump -- http://mail.python.org/mailman/listinfo/python-list
Re: Getting Python Accepted in my Organisation
Stuart Turner wrote: > "Python is a scripting language like Perl, awk, tcl, Java etc... it > is > not quite a fully developed OO language, but does support some OO that > Perl > doesn't. To be clear, these scripting languages have their place in > our > environment, but they are not full replacements for C#, Java, C, > etc... > because they do not come with the full range of libraries e.g GDI > libraries. Python has to be compared to Perl, Awk in order to > evaluate it. > Perl, until recently, did not support threading. Why would it? it is a > scripting language and can run async shell commands. I would be > interested > to learn if Python supports a robust threading model (not just a > pointer > reference to an object), as this is a significant drawback when using a > scripting language. CGI only works because the container can thread > with > Perl. Python is object orientated, but I do not know what > implementation? > Essentially any language with a pointer can claim to be OO, although > Python > does market itself on OO capabilities. Do you know what implementation > they have used? So, Java both is and is not a scripting language? My favourite article says it all in its title: http://www.python.org/pycon/dc2004/papers/6/ -- http://mail.python.org/mailman/listinfo/python-list
Re: Class Variable Access and Assignment
Op 2005-11-03, Stefan Arentz schreef <[EMAIL PROTECTED]>: > Antoon Pardon <[EMAIL PROTECTED]> writes: > >> Op 2005-11-03, venk schreef <[EMAIL PROTECTED]>: >> > You see, >> > The seen behavior is due to the result of python's name >> > binding,scoping scheme. >> >> I know what causes the behaviour. But I still think it is >> not sane behaviour. >> >> >> > ... >> > >> > the same thing happens in the case of b.a = b.a + 2 search for b.a >> > not found, read the value from the enclosing scope (of the class >> > object) then assign b.a to the local scope, with the value 3. >> >> This is an explanation depending on a specific implementation. >> >> Now can you give me a language design argument that supports the >> idea that in "b.a = b.a + 2" b.a refers to two different objects. >> >> And even if you could do that, can you give such an argument that >> in "b.a += 2" that one occurence of b.a should refer to two different >> objects. > > Your problem is a namespace conflict together with a certain > stubborness about lookup order :-) > > It is really simple. When you say b.a then the instance variable 'a' > is looked up first. If it does not exist then a class variable lookup > is done. Fine, we have the code: b.a += 2 We found the class variable, because there is no instance variable, then why is the class variable not incremented by two now? > Remember, Python is a dynamic language. So? Python being a dynamic language doesn't prevent the following to fail: >>> a=1 >>> def f(): ... a += 2 ... >>> f() Traceback (most recent call last): File "", line 1, in ? File "", line 2, in f UnboundLocalError: local variable 'a' referenced before assignment > It is all according to how things have been in Python for a long time. Unsane behaviour for a long time is still unsane behaviour. > The real issue here is that you should propery name class variables so > that there can't be any confusion about class or instance scope. I use > all uppercase identifiers for class variables for example. The fact that this can be regarded as unwise coding, doesn't imply it is sane behaviour of python. Variable shadowing happens. I don't consider it sane behaviour if the same reference in a line gets resolved in different name spaces -- Antoon Pardon -- http://mail.python.org/mailman/listinfo/python-list
Re: shared library search path
Stefan Arentz wrote:
>
> Hi. I've wrapped a C++ class with Boost.Python and that works great. But,
> I am now packaging my application so that it can be distributed. The
> structure is basically this:
>
> .../bin/foo.py
> .../lib/foo.so
> .../lib/bar.py
>
> In foo.py I do the following:
>
> sys.path.append(os.path.dirname(sys.path[0]) + '/lib')
>
> and this allows foo.py to import bar. Great.
>
> But, the foo.so cannot be imported. The import only succeeds if I place
> foo.so next to foo.py in the bin directory.
>
> I searched through the 2.4.2 documentation on python.org but I can't find
> a proper explanation on how the shared library loader works.
>
> Does anyone understand what it going on here?
>
> S.
>
No, but here is the code I use:
import sys
sys.path.append ('../wrap')
--
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Re: Class Variable Access and Assignment
Again (blink) quoting from the docs " For targets which are attribute references, the initial value is retrieved with a getattr() and the result is assigned with a setattr(). Notice that the two methods do not necessarily refer to the same variable. When getattr() refers to a class variable, setattr() still writes to an instance variable. For example: class A: x = 3# class variable a = A() a.x += 1 # writes a.x as 4 leaving A.x as 3 " I felt a wee bit clear after going thru the doc... attribute referencing is not the same as searching the variable in the enclosing scopes But, i still feel the inconsistency... -- http://mail.python.org/mailman/listinfo/python-list
Re: Forcing the position of scroll bars on a wxTextCtrl
Clans Of Intrigue wrote: > Thanks, that did the trick perfectly :) > > also got rid of the self._log member so the class is now just: > > class LogControl: > """ Simple helper to redirect stdout to a panel in the GUI """ > def __init__( self, textCtrl ): > self._ctrl = textCtrl > self.write( "Application Started..." ) > > def write( self, Message ): > # Add message to log and force scroll bars to end of window > self._ctrl.SetValue( self._ctrl.GetValue() + Message ) > self._ctrl.ShowPosition(self._ctrl.GetLastPosition()) But if you have 100kB text in the control, and add another 1kB log message, it certainly seems suboptimal to use: self._ctrl.SetValue( self._ctrl.GetValue() + Message ) Here, you first copy all the text in the control to a Python string, build a new string with old+new text, and replace the old text with the context of this bigger string. You should simply use self._ctrl.AppendText( Message ). I'm not sure exactly what happens under he hood, but I suspect that's more efficient, besides being prettier in the source... Thou shalt study thy libraries and strive not to reinvent them without cause, that thy code may be short and readable and thy days pleasant and productive. E.g. http://www.wxpython.org/docs/api/wx.TextCtrl-class.html -- http://mail.python.org/mailman/listinfo/python-list
Re: computer programming
Brandon K wrote: > what is .tk? Turkmenistan? or is it just some arbitrary suffix. Nope that's tm. Tokelau has tk. I'm sure you can learn more from Wikipedia etc. See e.g. http://en.wikipedia.org/wiki/ISO_3166-1 > >> www.javaholics.tk > > > > > == Posted via Newsgroups.com - Usenet Access to over 100,000 > Newsgroups == > Get Anonymous, Uncensored, Access to West and East Coast Server Farms! > == Highest Retention and Completion Rates! HTTP://WWW.NEWSGROUPS.COM > == > > -- http://mail.python.org/mailman/listinfo/python-list
Re: installing PygreSQL and psychopg2 modules (a newbie question)
On Wednesday 02 November 2005 14:10, Zlatko Matić wrote:
> Hello.
> I was trying to install PygreSQL and psychopg2 in order to use python
> as front-end for PostgreSQL, on WIndows XP. When I tried to install
> by calling setup.py from command prompt ("setup.py install"), in both
> cases I had the same error:
>
> "error: Python was built with version 7.1 of Visual Studio, and
> extensions need to be built with the same version of the compiler,
> but it isn't installed."
>
> It looks like this:
> "C:\Downloads\Python\psychopg\psycopg2-2.0b5\psycopg2-2.0b5>setup.py
> install running install
> running build
> running build_py
> running build_ext
> building 'psycopg2._psycopg' extension
> error: Python was built with version 7.1 of Visual Studio, and
> extensions need t
> o be built with the same version of the compiler, but it isn't
> installed.
>
> C:\Downloads\Python\psychopg\psycopg2-2.0b5\psycopg2-2.0b5>pause
> Press any key to continue . . ."
>
> What does it mean ? What am I supposed to do?
>
> Thanks,
>
> Zlatko
Use the windows installer for psycopg2. You can download it here:
http://stickpeople.com/projects/python/win-psycopg/psycopg2-2.0b5.win32-py2.4.exe
Tom
--
http://mail.python.org/mailman/listinfo/python-list
Re: Class Variable Access and Assignment
Antoon Pardon <[EMAIL PROTECTED]> writes: ... > Fine, we have the code: > > b.a += 2 > > We found the class variable, because there is no instance variable, > then why is the class variable not incremented by two now? Because it really is executed as: b.a = b.a + 2 1. get 't'b.a and store it in a temporary 't' (found the instance) 2. add 2 to 't' 3. store 't' in 'b.a' The last operation stores it into an instance variable. > > > Remember, Python is a dynamic language. > > So? Python being a dynamic language doesn't prevent the following to fail: > > >>> a=1 > >>> def f(): > ... a += 2 > ... > >>> f() > Traceback (most recent call last): > File "", line 1, in ? > File "", line 2, in f > UnboundLocalError: local variable 'a' referenced before assignment See the 'global' keyword. s. -- http://mail.python.org/mailman/listinfo/python-list
Re: Class Variable Access and Assignment
Stefan Arentz <[EMAIL PROTECTED]> writes: > Antoon Pardon <[EMAIL PROTECTED]> writes: > > ... > > > Fine, we have the code: > > > > b.a += 2 > > > > We found the class variable, because there is no instance variable, > > then why is the class variable not incremented by two now? > > Because it really is executed as: > > b.a = b.a + 2 > > 1. get 't'b.a and store it in a temporary 't' (found the instance) Oops. 1. get b.a and store it in a temporary 't' (found the class variable 'a') S. -- http://mail.python.org/mailman/listinfo/python-list
Re: Class Variable Access and Assignment
Op 2005-11-03, venk schreef <[EMAIL PROTECTED]>: > hey, > did u read my reply fully? i too feel that this matter of raising > unbound local error in one case and not raising it in the other must be > analysed... Yes, it seems I didn't respond to your satisfaction, but since you don't provide details I can't clarify. > quoting from the documentation > "If a name binding operation occurs anywhere within a code block, all > uses of the name within the block are treated as references to the > current block. This can lead to errors when a name is used within a > block before it is bound. This rule is subtle. Python lacks > declarations and allows name binding operations to occur anywhere > within a code block. The local variables of a code block can be > determined by scanning the entire text of the block for name binding > operations." Well I wonder. Would the following code be considered a name binding operation: b.a = 5 -- Antoon Pardon -- http://mail.python.org/mailman/listinfo/python-list
Re: installing PygreSQL and psychopg2 modules (a newbie question)
On 11/2/05, Zlatko Matić <[EMAIL PROTECTED]> wrote:
I was trying to install PygreSQL and psychopg2 in
order to use python as front-end for PostgreSQL, on WIndows XP.
When I tried to install by calling setup.py from
command prompt ("setup.py install"), in both cases I had the same
error:
"error: Python was built with version 7.1 of Visual
Studio, and extensions need to be built with the same version of the compiler,
but it isn't installed."
What does it mean ? What am I supposed to
do?
It means you are trying to install from source (I assume you downloaded
tarballs of pygresql and psycopg), and it needs a compiler to build the
source. Your Python was installed as a Windows binary, right? (you did
point-and-click install of Python?) It appears you do not have Visual
Studio installed on your system. I have no idea if these database
libraries will build with VS, I've never tried on Windows. Another
thing, you need all the postgres libraries and headers to build these
packages, and I don't know if postgres win32 includes these.
Rob
--
http://mail.python.org/mailman/listinfo/python-list
Re: Class Variable Access and Assignment
On Thu, 03 Nov 2005 04:30:09 -0800, Paul Rubin wrote: > Steve Holden <[EMAIL PROTECTED]> writes: >> > class A: >> > a = 1 >> > b = A() >> > b.a += 2 >> > print b.a >> > print A.a >> > Which results in >> > 3 >> > 1 >> > >> I don't suppose you'd care to enlighten us on what you'd regard as the >> superior outcome? > > class A: > a = [] > b = A() > b.append(3) > print b.a > print a.a > > Compare and contrast. I take it then that you believe that ints like 1 should be mutable like lists? Because that is what the suggested behaviour implies. Ah, what a grand thing that would be! We could say: 0 += 1 1 += 2 7 -= 1 and then have 0 + 1 == 7. Think of the obfuscated code we could write! -- Steven. -- http://mail.python.org/mailman/listinfo/python-list
Learning multiple languages (question for general discussion)
After my last post, I thought of another question as a result of the following: -- Mike Meyer wrote: > John Salerno <[EMAIL PROTECTED]> writes: > [Wants to learn C# and Python simultaneously.] > >>So my question is, is this feasible? > > > Should be. It might be faster to do them sequentually. -- I thought it might be interesting to get some opinions on when you know when you're "done" learning a language. I've been learning C# for a few months (albeit not intensively) and I feel I have a good grasp of the language in general. Of course, I haven't messed much with databases, or at all with ASP.NET...so far just WinForms. But as far as the syntax of the language, I understand that, as well as a lot of how the .NET Framework works. I know this is a very subjective situation, but when would you say that it's 'safe' to move on to another language? How do you define a language as being "learned"? For me, I'm just doing this for fun, but I imagine in the computer programming world, you constantly need to learn new things, so I wouldn't assume that you completely learn a language before moving on to another. -- http://mail.python.org/mailman/listinfo/python-list
Re: Class Variable Access and Assignment
Op 2005-11-03, venk schreef <[EMAIL PROTECTED]>: > Again (blink) quoting from the docs " > For targets which are attribute references, the initial value is > retrieved with a getattr() and the result is assigned with a setattr(). > Notice that the two methods do not necessarily refer to the same > variable. When getattr() refers to a class variable, setattr() still > writes to an instance variable. For example: > > class A: > x = 3# class variable > a = A() > a.x += 1 # writes a.x as 4 leaving A.x as 3 > " > > I felt a wee bit clear after going thru the doc... attribute > referencing is not the same as searching the variable in the enclosing > scopes But, i still feel the inconsistency... The documentation is IMO no help in arguing whether the behaviour is sane or not. Unsane documented behaviour is still unsane. So yes the documentation explains why such a result can happen, but that doesn't change the fact that in this case we have only one a.x on that line and the processing behind the scenes refers to an x in two different name spaces. I think that is unsane behaviour and giving an explanation on why this particular behaviour arises from the current implemenation doesn't change that. -- Antoon Pardon -- http://mail.python.org/mailman/listinfo/python-list
Re: weakrefs to functions for observer pattern
Alex Martelli wrote: > Michael Schneider <[EMAIL PROTECTED]> wrote: > > >>I would like to use weak refs in an observer pattern implementation. >>The problme that I have seems to be that weakrefs can't manage functions. > > > They can manage just fine functions written in *Python*, just not > "builtin functions*, i.e., ones written in *C*. Just wrap any builtin > function you need to register as observer into a tiny Python-coded > wrapper and live happily ever after. >... > >>Not all objects can be weakly referenced; those objects which can >>include class instances, functions written in Python (but not in C), > > > > Alex Alex, Thank you, I mis-read the docs. The mistake I made was having was using a weak reference as a key in the dictionary. Weak references will be very useful for me. I really enjoy python. So many good things have been added to the language without taking the fun away :-) Mike -- The greatest performance improvement occurs on the transition of from the non-working state to the working state. -- http://mail.python.org/mailman/listinfo/python-list
Re: how to associate files with application
Thanks Lasse, that was really helpful -- http://mail.python.org/mailman/listinfo/python-list
Re: Learning multiple languages (question for general discussion)
Am Thu, 03 Nov 2005 14:47:52 + schrieb John Salerno: > After my last post, I thought of another question as a result of the > following: > > -- > Mike Meyer wrote: > > John Salerno <[EMAIL PROTECTED]> writes: > > [Wants to learn C# and Python simultaneously.] > > > >>So my question is, is this feasible? > > > > > > Should be. It might be faster to do them sequentually. > -- Unfortunately there is not C# section in Pleac: http://pleac.sourceforge.net/ You can learn both languages by reading the python solutions in pleac, an try to translate them to C#. Please submit the code to the project. HTH, Thomas -- Thomas Güttler, http://www.thomas-guettler.de/ E-Mail: guettli (*) thomas-guettler + de Spam Catcher: [EMAIL PROTECTED] -- http://mail.python.org/mailman/listinfo/python-list
Re: Class Variable Access and Assignment
On Thu, 03 Nov 2005 12:50:51 +, Antoon Pardon wrote: >>> I don't care what should be different. But a line with only one >>> referent to an object in it, shouldn't be referring to two different >>> objects. >> >> It doesn't. > > Yes it does. If the b.a refers to the instance variable, then an > AttributeError should be raised, because the instance variable doesn't > exist yet, so you can't add two to it. Then you don't approve of inheritance? That's fine, it is your choice, but as far as I know, all OO languages include inheritance. I can't imagine why you would want this to happen: py> class BetterList(list): ... def wobble(self): ... """Wobble a list.""" ... pass ... py> L = BetterList((1, 2, 3)) py> L.sort() Traceback (most recent call last): File "", line 1, in ? AttributeError: 'BetterList' object has no attribute 'sort' (It just goes to show that Explicit is better than Implicit is not *always* true.) > If the b.a refers to the class variable then two should be added to it. > > Neither happens instead we get some hybrid in which an instance varible > is created that gets the value of class variable incrented by two. Which is precisely the expected behaviour. First you fetch the instance attribute, which by the rules of inheritance falls back to the value of the class attribute if it doesn't yet exist (which, in this specific case, it does not). Then you add two to it, and store the result in the instance attribute. You can't increment the object 1 because it is immutable. >>> In the line: b.a += 2, the b.a should be refering to the class >>> variable or the object variable but not both. So either it could raise >>> an attribute error or add two to the class variable. >> >> It does exactly what you say. It adds 2 to the a *instance variable* of >> the object instance in 'b'. > > There is no instance variable at that point. How can it add 2, to > something that doesn't exist at the moment. By the standard rules of inheritance. -- Steven. -- http://mail.python.org/mailman/listinfo/python-list
Re: another beginner sort of question
Thanks! Mike Meyer wrote: > John Salerno <[EMAIL PROTECTED]> writes: > [Wants to learn C# and Python simultaneously.] > >>So my question is, is this feasible? > > > Should be. It might be faster to do them sequentually. > > >>Or does learning Python require (or entail) learning all the details >>behind it? > > > Not really. There are some traps you can fall into that are obvious if > you know how the underlying implementation works, but even for those, > you just need the general idea, not the details. > > >>Also, do I need to know anything about C or C++? > > > No. In fact, the less you know about them, the less you'll have to > unlearn to use Python effectively. > > >>Python seems to connected to those languages that I'm afraid >>learning Python by itself might not be practical, but hopefully >>that's unfounded. > > > CPython (the implementation most people mean when they say "Python") > is written in C, and has well-defined APIs for putting an interpreter > into a C program, or making functionality from a C library available > to a CPython program. Other implementations have similar hooks for > different languages. Unless you want to get into the internals of an > implementation, to embed Python in an application, or to write a > Python extension (usually because you're wrapping an existing > library), you won't need to worry about any of these. > > One thing. While Python is called a "scripting language", it doesn't > have facilities for dealing with shell scripting that other "scripting > languages" have. As such, it's harder to do shell scripting type > things in Python than in those languages. On the other hand, it's > easier than doing them in C, for the same reason that doing pretty > much anything in Python is easier than doing it in C. On the gripping > hand, if you do things pythonically instead of like you'd do them in a > shell script, you may find that Python is easier than the shell > script. > > http://mail.python.org/mailman/listinfo/python-list
Re: Class Variable Access and Assignment
On Thu, 03 Nov 2005 12:53:37 +, Antoon Pardon wrote: >> I don't suppose you'd care to enlighten us on what you'd regard as the >> superior outcome? > > No. I don't think a superior outcome is necessary to see that this is > not sane behaviour. I don't care that much on how it gets fixed. It isn't broken, there is nothing to fix. The code does precisely what the inheritance model promises to do. -- Steven. -- http://mail.python.org/mailman/listinfo/python-list
Re: PEP submission broken?
Steve Holden wrote: > Volunteers don't always behave as perfect bureaucrats :-) Neither do typical bureaucrats! -- http://mail.python.org/mailman/listinfo/python-list
Re: How to print random strings
[EMAIL PROTECTED] wrote: > So how would I go about have 5 strings, and running a program that will > randomly pick one of those to print? >>> import random >>> text = "Perhaps reading the manual is a good idea?".split() >>> random.choice(text) 'is' >>> random.choice(text) 'reading' >>> random.choice(text) 'a' >>> random.choice(text) 'the' >>> random.choice(text) 'Perhaps' See http://docs.python.org/lib/module-random.html -- http://mail.python.org/mailman/listinfo/python-list
Re: Class Variable Access and Assignment
Antoon Pardon wrote: > Op 2005-11-03, Steven D'Aprano schreef <[EMAIL PROTECTED]>: > > >>>There are two possible fixes, either by prohibiting instance variables >>>with the same name as class variables, which would allow any reference >>>to an instance of the class assign/read the value of the variable. Or >>>to only allow class variables to be accessed via the class name itself. >> >>There is also a third fix: understand Python's OO model, especially >>inheritance, so that normal behaviour no longer surprises you. > > > No matter wat the OO model is, I don't think the following code > exhibits sane behaviour: > > class A: > a = 1 > > b = A() > b.a += 2 > print b.a > print A.a > > Which results in > > 3 > 1 On the other hand: >>> class C: ... a = [1] ... >>> b=C() >>> b.a += [2] >>> b.a [1, 2] >>> C.a [1, 2] I can understand that Guido was a bit reluctant to introduce += etc into Python, and it's important to understand that they typically behave differently for immutable and mutable objects. -- http://mail.python.org/mailman/listinfo/python-list
Re: Class Variable Access and Assignment
Antoon Pardon wrote: > There is no instance variable at that point. How can it add 2, to > something that doesn't exist at the moment. Because 'a += 1' is only a shorthand for 'a = a + 1' if a is an immutable object? Anyway, the behaviour is well documented. http://docs.python.org/ref/augassign.html says: An augmented assignment expression like x += 1 can be rewritten as x = x + 1 to achieve a similar, but not exactly equal effect. In the augmented version, x is only evaluated once. Also, when possible, the actual operation is performed in-place, meaning that rather than creating a new object and assigning that to the target, the old object is modified instead. ... For targets which are attribute references, the initial value is retrieved with a getattr() and the result is assigned with a setattr(). Notice that the two methods do not necessarily refer to the same variable. When getattr() refers to a class variable, setattr() still writes to an instance variable. For example: class A: x = 3# class variable a = A() a.x += 1 # writes a.x as 4 leaving A.x as 3 -- http://mail.python.org/mailman/listinfo/python-list
Re: Most efficient way of storing 1024*1024 bits
Alex Stapleton <[EMAIL PROTECTED]> wrote: ... > >>> Six megabytes is pretty much nothing on a modern computer. > > > >> BTW, it'd be 6 megabits or 750kb ;) > > > > ...but Mike was proposing using one digit per bit, hence, 6 megabytes. > > That makes it easy to search for bitpatterns with re or > > string.find; if > > the bits were packed 8 to a byte, such searches would be very hard. > > They would just require some out-of-the-box thinking using character > arrays and stuff I think. It's definately still doable with regex's > if you really want to. "Doable", yes, of course -- that's pretty obvious, and I'm not sure what's "out of the box" about it -- but orders of magnitude harder. For example, to look for a fixed sequence of X bits, you'd have to search for any of 8 sequences of slightly more than X/8 characters (where the first and last are normally charsets) built by the possible shifts of the bitsequence by 0, 1, ... 7 bits. I also suspect that performance would badly suffer (dealing with 750 KB of data, plus all the auxiliary stuff for Python and re, isn't going to fit in cache anyway). All in all, doesn't feel worth pursuing, particularly when the OP mentioned time mattering more than space right from the word go. Alex -- http://mail.python.org/mailman/listinfo/python-list
Re: Learning multiple languages (question for general discussion)
Python has spoiled me. I used to periodically try out new languages just for fun, but since learning Python, it's become a lot less interesting. I find myself preferring to just try new ideas or techniques in Python rather than searching for new languages to dabble in. The last few I've downloaded were, in no particular order: Perl, Ruby, Lisp, Io, and Scheme. I usually get as far as installing the necessary interpreters/compilers and opening up a tutorial or two before I lose interest. -- http://mail.python.org/mailman/listinfo/python-list
Re: Getting Python Accepted in my Organisation
I have done the same thing in my organisation. Show them concrete examples of when they can benefit from Python to Convince them. My colleagues and bosses has been conviced and therefore my current work task is to integrate the interpreter in a VxWorks environment so "everyone" at the company can use it within our context. If you are good at convincing you can be lucky and get some fun work tasks. :) Good luck! //T -- http://mail.python.org/mailman/listinfo/python-list
How can I package a python script and modules into a single script?
I would like to package my main script and all the modules it imports into a single script that will run just as the collection would. It should not need to package standard Python lib modules -- just my local modules. This is not the same question that would be answered with py2exe or py2app. I don't need to package the script into a binary along with Python. I expect Python to be installed. I also don't want to use distutils to install the script. The script will always run on Unix. I thought that there might be some way to run a script package from a tar file. One way would be to have the package script untar itself into a temp directory; run the main script; then delete the temporary package directory when done. That sounds clunky and prone to leave around trash if someone does a 'kill -9'. However, this might be an acceptable compromise. I'm sure that I've seen a tool around like this, but I can't find it anymore. I checked the usual places (google and sf.net). I also considered simply cutting and pasting all the modules I need into one single, giant script, but that's less appealing than the tarball idea (unless it could be done automatically). Yours, Noah -- http://mail.python.org/mailman/listinfo/python-list
Re: Python and MySQL
"Steve Holden" <[EMAIL PROTECTED]> wrote in message news:[EMAIL PROTECTED] > Thomas Bartkus wrote: > > "Steve Holden" <[EMAIL PROTECTED]> wrote in message > > news:[EMAIL PROTECTED] > > > >>I have a _mysql.c as a part of my distrbution of MySQLdb. Don't you? > >> > > > > > > You made me give that library a good hard stare. > > > > And no - everything is enunciated in clear Python (.py) code with > > corresponding (.pyc) and (.pyo). It appears we have Python source for > > everything. > > > >FWIW: > > > > > print MySQLdb.version_info > > > > (1, 2, 0, 'final', 1) > > > OK. I saw that my own version was (1, 0, 0, 'final', 1), so I assumed > Andy's updated the package somewhat. However, downloading the source of > 1.2 I see that _mysql.c still appears, and that the package's > __init__.py still includes the line > > include _mysql > > My C:\Python24\Lib\site-packages directory does contain a _mylsql.pyd > file. Would you like to check that we are talking about the same module? Okay - I neglected to look at the [site-packages] directory itself. Here I do find [_mysql.pyd] full of binary code. A MySQLdb related file that doesn't seem to have a corresponding file with Python source code. Mea culpa! This is on MS Windows [C:\Python23]. But heck! Now I'm looking at the /usr/lib/python2.3/site-packages on a Mandrake Linux box. No [_mysql.] pyd here! Fewer files overall and while there are other file extensions, everything seems to have a corresponding [.py]. print MySQLdb.version_info (0, 9, 2, 'final', 1) Thomas Bartkus -- http://mail.python.org/mailman/listinfo/python-list
Re: Learning multiple languages (question for general discussion)
LOL. As weird as it sounds, that's what I *don't* want to happen with C#! I've spent a lot of time with it, and I love it, but I don't want Python to take over! :) infidel wrote: > Python has spoiled me. I used to periodically try out new languages > just for fun, but since learning Python, it's become a lot less > interesting. I find myself preferring to just try new ideas or > techniques in Python rather than searching for new languages to dabble > in. The last few I've downloaded were, in no particular order: Perl, > Ruby, Lisp, Io, and Scheme. I usually get as far as installing the > necessary interpreters/compilers and opening up a tutorial or two > before I lose interest. > -- http://mail.python.org/mailman/listinfo/python-list
Re: NTFS reparse points
Stanislaw Findeisen wrote:
> (2) Does anybody have any idea (sample code?) on how to create a reparse
> point (the simpler, the better) using Python?
>
The only sample code I've seen for creating reparse points is in c or c++
and its quite a messy operation. See
http://www.sysinternals.com/Utilities/Junction.html for some sample code.
The easy way to do it from Python is just to make sure you have a program
such as junction on your system then use os.system('junction "%s" "%s"' %
(directory, target))
Be careful if you start creating junctions: Windows explorer doesn't
understand them: if you try to delete a folder which is actually a junction
it first deletes all the files inside the folder so the original folder
ends up empty as well.
--
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