Re: Striving for PEP-8 compliance
In message <18988a53-e88f-4abf- a83a-314b16653...@x12g2000yqx.googlegroups.com>, Patrick Maupin wrote: > I want nothing to do with any programmer who would mis-indent their > code. But what happens when you’re trying to reconcile two different indentation conventions? In Python, there can be problems doing that without introducing logic errors. That’s what this thread is about. -- http://mail.python.org/mailman/listinfo/python-list
Re: Striving for PEP-8 compliance
In message , Grant Edwards wrote: > On 2010-04-10, Lawrence D'Oliveiro > wrote: > >> In message , Grant Edwards wrote: >> >>> Anybody who invents another brace-delimited language should be beaten. >>> You always end up with a big problem trying to make sure the braces >>> are consistent with the program logic. > >> Would you prefer ???begin??? and ???end??? word symbols, then? > > Nope, I categorize those as nothing more than verbose "braces". But since those symbols already, by definition, directly correspond to program logic, where exactly does the “big problem” arise trying to make sure they are “consistent with the program logic”? -- http://mail.python.org/mailman/listinfo/python-list
Re: How to read file during module import?
Jeremy wrote: I have a module that, when loaded, reads and parses a supporting file. The supporting file contains all the data for the module and the function that reads/parses the file sets up the data structure for the module. How can I locate the file during the import statement. The supporting file is located in the same directory as the module, but when I import I get a No such file or directory error. I could hard code the path to the filename, but that would make it only work on my machine. A related question: Can I parse the data once and keep it somewhere instead of reading the supporting file every time? I tried pickling but that wouldn't work because I have custom classes. (Either that or I just don't know how to pickle—this is a highly probable event.) Thanks, Jeremy By supporting file, presumably you mean a text or binary file, not a python module. That's why import won't work. Now, if the data supports it, you could make that supporting file simply be an importable python program. I've seen code generators to create python code from a binary file such as a jpeg, so that you can just embed such code into your program. But I'll guess that this isn't reasonable for your data, that the format is something you want to separately manipulate. I think the secret you're looking for is the __file__ attribute of a module. That contains the full path to the module source file (.py or .pyc, usually). So you use dirname on that string, to get the directory name, and os.path.join to combine with your own filename. Now you have a string to pass to open(). DaveA -- http://mail.python.org/mailman/listinfo/python-list
Re: Pythonic list reordering
Ben Racine writes:
> I have a list...
>
> ['dir_0_error.dat', 'dir_120_error.dat', 'dir_30_error.dat',
> 'dir_330_error.dat']
>
> I want to sort it based upon the numerical value only.
>
> Does someone have an elegant solution to this?
I use code like the hack below to sort miscellaneous strings that
consist of mixed numerical and non-numerical parts.
import re
nsk_re = re.compile("([0-9]+)|([^0-9]+)")
def numeric_sort_key(x):
return [handle_int_nonint(i_ni) for i_ni in nsk_re.findall(x)]
def handle_int_nonint(int_nonint_tuple):
if int_nonint_tuple[0]:
return int(int_nonint_tuple[0])
else:
return int_nonint_tuple[1]
def numerically_sorted(l):
return sorted(l, key=numeric_sort_key)
--
http://mail.python.org/mailman/listinfo/python-list
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Re: Performance of list vs. set equality operations
Steven D'Aprano, 08.04.2010 03:41: On Wed, 07 Apr 2010 10:55:10 -0700, Raymond Hettinger wrote: [Gustavo Nare] In other words: The more different elements two collections have, the faster it is to compare them as sets. And as a consequence, the more equivalent elements two collections have, the faster it is to compare them as lists. Is this correct? If two collections are equal, then comparing them as a set is always slower than comparing them as a list. Both have to call __eq__ for every element, but sets have to search for each element while lists can just iterate over consecutive pointers. If the two collections have unequal sizes, then both ways immediately return unequal. Perhaps I'm misinterpreting what you are saying, but I can't confirm that behaviour, at least not for subclasses of list: >>> class MyList(list): ... def __len__(self): ... return self.n ... >>> L1 = MyList(range(10)) >>> L2 = MyList(range(10)) >>> L1.n = 9 >>> L2.n = 10 >>> L1 == L2 True >>> len(L1) == len(L2) False This code incorrectly assumes that overriding __len__ has an impact on the equality of two lists. If you want to influence the equality, you need to override __eq__. If you don't, the original implementation is free to do whatever it likes to determine if it is equal to another value or not. If it uses __len__ for that or not is only an implementation detail that can't be relied upon. Stefan -- http://mail.python.org/mailman/listinfo/python-list
Re: Striving for PEP-8 compliance
I'm interested that you are holding what appear to be contradictory arguments, and don't seem to apply each one to the other. Let me take the latest expressions of these and show how they can apply equally in either direction: Lawrence D'Oliveiro writes: > But what happens when you’re trying to reconcile two different > indentation conventions? In Python, there can be problems doing that > without introducing logic errors. What happens whe you're trying to reconcile two different block-delimiter conventions? Lawrence D'Oliveiro writes: > But since [braces] already, by definition, directly correspond to > program logic, where exactly does the “big problem” arise trying to > make sure they are “consistent with the program logic”? Since indentation already, by definition, directly corresponds to program logic in Python, where exactly is the problem that leads you to want to eradicate indentation as syntax? In other words: I don't see why the problems you're asserting are problematic for one kind of block delimitation syntax but not the other. -- \ “[Freedom of speech] isn't something somebody else gives you. | `\ That's something you give to yourself.” —_Hocus Pocus_, Kurt | _o__) Vonnegut | Ben Finney -- http://mail.python.org/mailman/listinfo/python-list
Re: Striving for PEP-8 compliance
On 2010-04-10, Lawrence D'Oliveiro wrote: > In message , Grant Edwards wrote: > >> On 2010-04-10, Lawrence D'Oliveiro >> wrote: >> >>> In message , Grant Edwards wrote: >>> Anybody who invents another brace-delimited language should be beaten. You always end up with a big problem trying to make sure the braces are consistent with the program logic. >> >>> Would you prefer ???begin??? and ???end??? word symbols, then? >> >> Nope, I categorize those as nothing more than verbose "braces". > > But since those symbols already, by definition, directly correspond to > program logic, where exactly does the ?big problem? arise trying to make > sure they are ?consistent with the program logic?? The same goes for indentation. In python it's not possible to write a program to correctly indent code that isn't alaready correctly indented. In a brace delimited language it's not possible to write a program to correctly place braces in an "incorrectly braced" program. In either: if it is already correct, it's trivial to transform it into another correct program with a different "style". -- -- http://mail.python.org/mailman/listinfo/python-list
Re: python as pen and paper substitute
Michael Torrie writes: > > Did you look at the link to Owen Taylor's reinteract program? I think > it's closer to what you want than any other thing mentioned here, with > the exception that it's a standalone GTK (graphical) app. Yes, I did. And I think this program is a great lightweight alernative to sage, which was mentioned in another post and would probably be my preferred environment if I had complete freedom to set up my working environment and would not need to exchange data with others or explain how someone else is supposed to reuse my code/results in two years time. Things being as they are, I am looking for a solution which works with as few additional components as possible, so that a solution based on a simple copy-and-paste class or decorator is preferable. Regards, Manuel -- A hundred men did the rational thing. The sum of those rational choices was called panic. Neal Stephenson -- System of the world http://www.graune.org/GnuPG_pubkey.asc Key fingerprint = 1E44 9CBD DEE4 9E07 5E0A 5828 5476 7E92 2DB4 3C99 -- http://mail.python.org/mailman/listinfo/python-list
Re: braceless and semicolonless
Hi Peter,
In PythoidC, I handled C header files (and other C files for INCLUDE) with
Python regular expression (RE).
First, I use the following RE to break C header files or C files into pieces
sepRE=_re.compile(r'\; | \{ | \} | // | /\* | \*/ | \r?\n',_re.VERBOSE)
Then, I carefully designed a loop testing each of the seperaters between
adjacent pieces
for sep in sepRE.finditer(f0c):
...
if sg==';':
cItems.append(f0c[span0:ss1].strip())
span0 = ss1
...
to reassemble several (may be one) consequent pieces into items (a function, a
struct, a constant ...)
At last I classify the items with some REs like
structRE=_re.compile(r'^(struct\s+([0-9A-Za-z_]+)\s*\{.+\}.*\;)$',_re.IGNORECASE|_re.DOTALL)
and arranged the items into Python objects with setattr(...)
You can download and read the source code of PythoidC at http://pythoidc.sf.net
or http://pythoidc.googlecode.com
If you feel PHP not good enough, I'd like to suggest Python ( www.python.org ).
Python is really an excellent language, with Python you can program softwares
for almost any porpose (except for hardware drivers and some software with very
high requirement of speed, now PythoidC is just the extension for Python in
such areas ).
Welcome to join the Python mailing list
http://mail.python.org/mailman/listinfo/python-list to discuss Python
techniques, there are many warm-hearted friends willingly to answer almost any
questions.
By the way, I work in China Medical University, Shenyang, northeast China. Will
you tell me something about youself?
Best Regards,
ChenGuang
2010-04-09 22:24:27，"Peter West" ：
Hi Chen,
My project uses a tree structured linked list to break down PHP into chunks, It
was necessary because PHP has a lot of syntaxes for strings. Some parts of the
language like one line comments and heredocs were quite a lot of trouble. How
have you handled the pre-processor? I briefly considered modifying my project
for C but the pre-processor's features would be difficult to handle. I'll try
to find you an example.
What other features would you like to add? In PHP I'm trying to add some useful
syntaxes such as calling an index of an array without assigning the array to a
variable e.g. $object->getArray()[0]. Another is instantiating an object and
using it in the same statement e.g. ($object new Class)->method().
Unfortunately PHP is not a very good language and there are only a few things I
can change about it.
Peter.
2010/4/9 CHEN Guang
Dear Peter,
I am the developer of PythoidC (braceless and semicolonless C language). I am
so glad to see your message, just like a message from Voyager 2 spacecraft,
telling me that I am nolonger alone in the universe!
My plan is to release new versions of PythoidC from time to time, adding new
applications and more examples.
My hope is that our ideal (braceless and semicolonless) will be shared by more
people in the world, thus lead to the simplification of all computer languages
(Java, Perl ...)
Let's talk often.
ChenGuang
--
http://mail.python.org/mailman/listinfo/python-list
On Class namespaces, calling methods
Still learning python, especially OOP. While testing classes, I sometimes think of them as "ordinary containers" of values and functions (methods). That is, values and functions can be grouped together inside "namespaces" calles classes. class Uno: a=1 def m(): print "mouse" Say that I have this "silly" class. While I can then write print Uno.a I cannot write Uno.m() I get the following error message: TypeError: m() takes no arguments (1 given) Since I have not created any instances of Uno, there is no self object, and I do not understand what object is supplied to the function call. Could anybody explain what argument is being supplied to the method? Is ther any workaround to call the m function? Thank you -- http://mail.python.org/mailman/listinfo/python-list
Re: Clearing memory (namespace) before running code
On Mar 21, 5:18 pm, Jon Clements wrote: > On 21 Mar, 15:02, vsoler wrote: > > > Hi, > > > Is there a way to erase/delete/clear memory before a piece of code is > > run? > > > Otherwise, the objects of the previous run are re-usable, and may > > bring confusion to the tester. > > > Thank you > > I'm guessing you're using some sort of IDE? > > For instance, in IDLE if the [Python Shell] window is not closed, the > session is kept. However, there is a menu option 'Shell' which has > 'Restart Shell'. If you don't see a 'Shell' menu option, then make > sure IDLE isn't being started with the -n option. > > However I would have thought the 'tester' would be running from a > terminal/command line/double click jobby, so that a single Python > session is executed and just runs -- rather than want to use it > interactively afterwards. > > hth > > Jon. Hello Jon, I'm using PythonWin and there is no Shell menu option. And yes, I am using python interactively. Perhaps it is simply impossible to delete all the attributes of a namespace in a single shot? -- http://mail.python.org/mailman/listinfo/python-list
ANN: obfuscate 0.2.2
I am pleased to announce the first stable release of obfuscate, version 0.2.2. http://pypi.python.org/pypi/obfuscate/ obfuscate is a pure-Python module providing classical encryption algorithms suitable for obfuscating and unobfuscating text. This is a maintenance release of back-end and API changes but no new ciphers. This should be considered the first stable API for obfuscate. obfuscate includes the following ciphers: - rot13, rot5, rot18, rot47 - atbash - Caesar cipher - Keyword - Affine - Playfair, Playfair6, Playfair16 - frob (xor) - Vigenere - RailFence - plus others. DISCLAIMER: obfuscate is not cryptographically strong, and should not be used where high security is required. obfuscate is released under the MIT licence. Requires Python 2.5 or 2.6. -- Steven -- http://mail.python.org/mailman/listinfo/python-list
Re: On Class namespaces, calling methods
vsoler wrote: > I get the following error message: > > TypeError: m() takes no arguments (1 given) > > Since I have not created any instances of Uno, there is no self > object, and I do not understand what object is supplied to the > function call. > > Could anybody explain what argument is being supplied to the method? > Is ther any workaround to call the m function? > Which version of Python are you using? Python 2.6 gives: TypeError: unbound method m() must be called with Uno instance as first argument (got nothing instead) whereas Python 3.1 gives: >>> Uno.m() mouse (assuming you change the print statement to work on Python 3.x) -- http://mail.python.org/mailman/listinfo/python-list
Re: On Class namespaces, calling methods
On 4/10/10, vsoler wrote: > Still learning python, especially OOP. > > While testing classes, I sometimes think of them as "ordinary > containers" of values and functions (methods). That is, values and > functions can be grouped together inside "namespaces" calles classes. > > class Uno: > a=1 > def m(): def m(self): > print "mouse" print "mouse" #I believe > > Say that I have this "silly" class. > > While I can then write > > print Uno.a > > I cannot write > Uno.m() > > I get the following error message: > > TypeError: m() takes no arguments (1 given) > > Since I have not created any instances of Uno, there is no self > object, and I do not understand what object is supplied to the > function call. I believe that self is always passed, whether you have an instance of the uno class or not. Since you did not tell m() to expect self to be passed to it, and self is passed anyway, m() has this self and has no idea what to do with it. Also, you must make an uno object (u=uno()) then call methods off that object (u.m()) since not doing so means the uno class will not get initialized. > > Could anybody explain what argument is being supplied to the method? > Is ther any workaround to call the m function? > > Thank you > -- > http://mail.python.org/mailman/listinfo/python-list > -- Have a great day, Alex (msg sent from GMail website) mehg...@gmail.com; http://www.facebook.com/mehgcap -- http://mail.python.org/mailman/listinfo/python-list
Re: Pythonic list reordering
On Apr 9, 8:52 am, Ben Racine wrote: > I have a list... > ['dir_0_error.dat', 'dir_120_error.dat', 'dir_30_error.dat', > 'dir_330_error.dat'] > I want to sort it based upon the numerical value only. > Does someone have an elegant solution to this? This approach doesn't rely on knowing the format of the string: >>> from string import maketrans, letters, punctuation >>> a = ['dir_0_error.dat', 'dir_120_error.dat', 'dir_30_error.dat', >>> 'dir_330_error.dat'] >>> def only_numbers(s): ... nums = s.translate(None, letters+punctuation) ... return int(nums) ... >>> a.sort(key=only_numbers) >>> a ['dir_0_error.dat', 'dir_30_error.dat', 'dir_120_error.dat', 'dir_330_error.dat'] If you're using Python 3.x, the string module has been removed, so you can find the maketrans function on str there. -- http://mail.python.org/mailman/listinfo/python-list
Re: Pythonic list reordering
alex23 wrote: On Apr 9, 8:52 am, Ben Racine wrote: I have a list... ['dir_0_error.dat', 'dir_120_error.dat', 'dir_30_error.dat', 'dir_330_error.dat'] I want to sort it based upon the numerical value only. Does someone have an elegant solution to this? This approach doesn't rely on knowing the format of the string: from string import maketrans, letters, punctuation a = ['dir_0_error.dat', 'dir_120_error.dat', 'dir_30_error.dat', 'dir_330_error.dat'] def only_numbers(s): ... nums = s.translate(None, letters+punctuation) ... return int(nums) ... a.sort(key=only_numbers) a ['dir_0_error.dat', 'dir_30_error.dat', 'dir_120_error.dat', 'dir_330_error.dat'] If you're using Python 3.x, the string module has been removed, so you can find the maketrans function on str there. The string module still exists in Python 3.x, but the string functions which have been superseded by string methods have been removed. -- http://mail.python.org/mailman/listinfo/python-list
Re: On Class namespaces, calling methods
On Apr 10, 4:46 pm, Duncan Booth wrote: > vsoler wrote: > > I get the following error message: > > > TypeError: m() takes no arguments (1 given) > > > Since I have not created any instances of Uno, there is no self > > object, and I do not understand what object is supplied to the > > function call. > > > Could anybody explain what argument is being supplied to the method? > > Is ther any workaround to call the m function? > > Which version of Python are you using? Python 2.6 gives: > > TypeError: unbound method m() must be called with Uno instance as first > argument (got nothing instead) > > whereas Python 3.1 gives: > > >>> Uno.m() > > mouse > > (assuming you change the print statement to work on Python 3.x) Hello Duncan, I am using ver 2.6, under PythonWin The feedback that I get from python is exactly this one: >>> print Uno.a 1 >>> Uno.m() Traceback (most recent call last): File "", line 1, in TypeError: m() takes no arguments (1 given) >>> -- http://mail.python.org/mailman/listinfo/python-list
Re: On Class namespaces, calling methods
On Apr 10, 4:46 pm, Duncan Booth wrote: > vsoler wrote: > > I get the following error message: > > > TypeError: m() takes no arguments (1 given) > > > Since I have not created any instances of Uno, there is no self > > object, and I do not understand what object is supplied to the > > function call. > > > Could anybody explain what argument is being supplied to the method? > > Is ther any workaround to call the m function? > > Which version of Python are you using? Python 2.6 gives: > > TypeError: unbound method m() must be called with Uno instance as first > argument (got nothing instead) > > whereas Python 3.1 gives: > > >>> Uno.m() > > mouse > > (assuming you change the print statement to work on Python 3.x) Hello Duncan, Your error message is correct if you use class Uno(object): However, the error message is different underclass Uno: Regards -- http://mail.python.org/mailman/listinfo/python-list
Re: Pythonic list reordering
MRAB wrote: > The string module still exists in Python 3.x, but the string functions > which have been superseded by string methods have been removed. Awesome, thanks for the heads up. -- http://mail.python.org/mailman/listinfo/python-list
Re: On Class namespaces, calling methods
class Uno: a=1 def m(): print "mouse" Say that I have this "silly" class. While I can then write print Uno.a I cannot write Uno.m() I get the following error message: TypeError: m() takes no arguments (1 given) As a workaround, use this pattern: >>> class Uno(object): ... @classmethod ... def m(cls): ... print "mouse" ... >>> Uno.m() mouse Since I have not created any instances of Uno, there is no self object, and I do not understand what object is supplied to the function call. The method is not actually called, so nothing is supplied. The error is raised when it turns out that the number of actual parameters and the number of formal parameters are different. This is how you call a method: #1. you try to call Uno.m() - the 'm' method object is found and taken #2. argument values are evaluated and taken (in your example, there are no arguments) #3. an extra argument is inserted in front of the argument list. This parameter is the object you where calling the method on. In this case, it is the 'Uno' class. #4. actual arguments are assigned to formal parameters. If this fails for some reason, an exception is raised. In your case - the number of actual parameters is one, the number of formal parameters is zero. This is why you get an exception. #5. If actual and formal parameters are matched, then the implicit self parameter is checked. If you call a method, then it must be an instance of the class being called (or an instanc of its subclass). For classmethods, it must be the same class (or a subclass of it). #6. Function body executed, value returned The implicit parameter (the instance, or for classmethods, the class) is ALWAYS added. So if you change your code: class Uno: def m(self): pass Then you won't get an exception in #4. But you will in #5, because instance methods must be called on an instance, not on a class. You can create a classmethod (e.g. with the @classmethod decorator) as shown above, and it will work. Could anybody explain what argument is being supplied to the method? Is ther any workaround to call the m function? Thank you -- http://mail.python.org/mailman/listinfo/python-list
Re: Python and Regular Expressions
On 2010-04-08, Richard Lamboj wrote: > If someone knows good links to this thema, or can explain how > parsers should/could work, please post it, or explain it. > > Thanks for the Informations and the Help! I liked Crenshaw's "Let's Build a Compiler!". It's pretty trivial to convert his Pascal to Python, and you'll get to basic parsing in no time. URL:http://compilers.iecc.com/crenshaw/ -- Neil Cerutti -- http://mail.python.org/mailman/listinfo/python-list
Re: Striving for PEP-8 compliance
On Apr 10, 5:10 am, Lawrence D'Oliveiro wrote: > In message <18988a53-e88f-4abf- > > a83a-314b16653...@x12g2000yqx.googlegroups.com>, Patrick Maupin wrote: > > I want nothing to do with any programmer who would mis-indent their > > code. > > But what happens when you’re trying to reconcile two different indentation > conventions? In Python, there can be problems doing that without introducing > logic errors. That’s what this thread is about. Well, I think Steven pointed out how this isn't usually, really, a problem, and I tried to point out (in a section of my posting you didn't quote) that you will have to deal with stupid little nits in life no matter which way you go. Personally, for me, this particular thing is a non-issue. If I'm getting a code snippet from somewhere, fixing it up is not a problem, and if I'm using a module or more from somewhere, I am not obsessive about changing it to PEP 8. Regards, Pat -- http://mail.python.org/mailman/listinfo/python-list
Re: On Class namespaces, calling methods
On Apr 10, 5:28 pm, Laszlo Nagy wrote: > > class Uno: > > a=1 > > def m(): > > print "mouse" > > > Say that I have this "silly" class. > > > While I can then write > > > print Uno.a > > > I cannot write > > Uno.m() > > > I get the following error message: > > > TypeError: m() takes no arguments (1 given) > > As a workaround, use this pattern: > > >>> class Uno(object): > ... @classmethod > ... def m(cls): > ... print "mouse" > ... > >>> Uno.m() > mouse > > > Since I have not created any instances of Uno, there is no self > > object, and I do not understand what object is supplied to the > > function call. > > The method is not actually called, so nothing is supplied. The error is > raised when it turns out that the number of actual parameters and the > number of formal parameters are different. > > This is how you call a method: > > #1. you try to call Uno.m() - the 'm' method object is found and taken > #2. argument values are evaluated and taken (in your example, there are > no arguments) > #3. an extra argument is inserted in front of the argument list. This > parameter is the object you where calling the method on. In this case, > it is the 'Uno' class. > #4. actual arguments are assigned to formal parameters. If this fails > for some reason, an exception is raised. In your case - the number of > actual parameters is one, the number of formal parameters is zero. This > is why you get an exception. > #5. If actual and formal parameters are matched, then the implicit self > parameter is checked. If you call a method, then it must be an instance > of the class being called (or an instanc of its subclass). For > classmethods, it must be the same class (or a subclass of it). > #6. Function body executed, value returned > > The implicit parameter (the instance, or for classmethods, the class) is > ALWAYS added. So if you change your code: > > class Uno: > def m(self): > pass > > Then you won't get an exception in #4. But you will in #5, because > instance methods must be called on an instance, not on a class. You can > create a classmethod (e.g. with the @classmethod decorator) as shown > above, and it will work. > > > Could anybody explain what argument is being supplied to the method? > > Is ther any workaround to call the m function? > > > Thank you > > Hi Laszlo, It's perfectly clear. Thank you very much -- http://mail.python.org/mailman/listinfo/python-list
Re: On Class namespaces, calling methods
On Apr 10, 9:26 am, vsoler wrote: > class Uno: > a=1 > def m(): > print "mouse" > ... > I cannot write > Uno.m() By default (at least in Python 2.x), Python will pass any function which is accessed through getattr on class or instance (usually called a "method") an instance of the class as the first parameter. You can avoid this by using the @staticmethod decorator in front: class Uno: a = 1 @staticmethod def m(): print "mouse" Then you can call Uno.m() directly. This puts a "staticmethod" wrapper around m(), which explains to the interpreter not to try to pass it the instance variable. Also useful is @classmethod. Interestingly, if you don't use staticmethod, the value in the class's dictionary is an ordinary function, but if you do use staticmethod, you no longer have a callable function in the class's dictionary: >>> class fred: ... def m(): ...print "foo" ... >>> fred.__dict__['m']() foo >>> class fred: ... @staticmethod ... def m(): ...print "foo" ... >>> fred.__dict__['m']() Traceback (most recent call last): File "", line 1, in TypeError: 'staticmethod' object is not callable HTH, Pat Regards, Pat -- http://mail.python.org/mailman/listinfo/python-list
finding objects in a piece of functional code ?
hello,
I would like to translate some functional description into some standard
class object,
so it can be used as a basic building brick into a larger piece of code.
Suppose the functional description is:
Name = 'Test_Function'
Out = 3 * In
That's all I would like to write.
So it should be translated into something :
class Test_Function ( basic_buidling_brick ) :
Orginal_Description = """
Name = 'Test_Function'
Out = 3 * In
"""
def Run ( self, Inputs ) :
Output = 3 * Input
return Output
One of the tasks is to find all "objects" in the functional code.,
so the translator can ask additional information for input/output/memory
variables.
The best I can think of is something like this:
>>> my={}
>>> my2=copy.copy(my)
>>> exec('A=3; B=4; C=A*B; print A,B,C',my)
3 4 12
>>> for item in my :
... if item not in my2 :
... print item
...
__builtins__
A
C
B
But this doesn't work, if I use a not yet definied variable (like "In"
in the example above).
Are there better ways ?
Or even better are there programs or libraries that can perfom such a
translation ?
thanks,
Stef Mientki
--
http://mail.python.org/mailman/listinfo/python-list
Tempering Client Expectations (OT)
Hi; I'm working with my first client where I've developed a custom script. I way underbid the project and I ate that as part of my learning experience. We outlined as precisely as I knew how what functionality was needed. Then he went to input data and lo and behold he needed more functionality. I told him that would require more investment. This went on a few times and now he's hopping mad about being nickeled and dimed to death. I bet this sounds familiar to you all, doesn't it? Good thing he's also a personal friend...we will survive this. But this red flag has caught my attention. Any good articles out there (or other advice) on how to deal with a situation like this? TIA, beno -- http://mail.python.org/mailman/listinfo/python-list
Re: Python and Regular Expressions
On Apr 8, 5:13 am, Nobody wrote: > On Wed, 07 Apr 2010 18:25:36 -0700, Patrick Maupin wrote: > >> Regular expressions != Parsers > > > True, but lots of parsers *use* regular expressions in their > > tokenizers. In fact, if you have a pure Python parser, you can often > > get huge performance gains by rearranging your code slightly so that > > you can use regular expressions in your tokenizer, because that > > effectively gives you access to a fast, specialized C library that is > > built into practically every Python interpreter on the planet. > Unfortunately, a typical regexp library (including Python's) doesn't allow > you to match against a set of regexps, returning the index of which one > matched. Which is what you really want for a tokeniser. Actually, there is some not very-well-documented code in the re module that will let you do exactly that. But even not using that code, using a first cut of re.split() or re.finditer() to break the string apart into tokens (without yet classifying them) is usually a huge performance win over anything else in the standard library (or that you could write in pure Python) for this task. > >> Every time someone tries to parse nested structures using regular > >> expressions, Jamie Zawinski kills a puppy. > > > And yet, if you are parsing stuff in Python, and your parser doesn't > > use some specialized C code for tokenization (which will probably be > > regular expressions unless you are using mxtexttools or some other > > specialized C tokenizer code), your nested structure parser will be > > dog slow. > > The point is that you *cannot* match arbitrarily-nested expressions using > regexps. You could, in theory, write a regexp which will match any valid > syntax up to N levels of nesting, for any finite N. But in practice, the > regexp is going to look horrible (and is probably going to be quite > inefficient if the regexp library uses backtracking rather than a DFA). Trust me, I already knew that. But what you just wrote is a much more useful thing to tell the OP than "Every time someone tries to parse nested structures using regular expressions, Jamie Zawinski kills a puppy" which is what I was responding to. And right after regurgitating that inside joke, Chris Rebert then went on to say "Try using an *actual* parser, such as Pyparsing". Which is all well and good, except then the OP will download pyparsing, take a look, realize that it uses regexps under the hood, and possibly be very confused. > Even tokenising with Python's regexp interface is inefficient if the > number of token types is large, as you have to test against each regexp > sequentially. It's not that bad if you do it right. You can first rip things apart, then use a dict-based scheme to categorize them. > Ultimately, if you want an efficient parser, you need something with a C > component, e.g. Plex. There is no doubt that you can get better performance with C than with Python. But, for a lot of tasks, the Python performance is acceptable, and, as always, algorithm, algorithm, algorithm... A case in point. My pure Python RSON parser is faster on my computer on a real-world dataset of JSON data than the json decoder that comes with Python 2.6, *even with* the json decoder's C speedups enabled. Having said that, the current subversion pure Python simplejson parser is slightly faster than my RSON parser, and the C reimplementation of the parser in current subversion simplejson completely blows the doors off my RSON parser. So, a naive translation to C, even by an experienced programmer, may not do as much for you as an algorithm rework. Regards, Pat -- http://mail.python.org/mailman/listinfo/python-list
Re: On Class namespaces, calling methods
vsoler wrote: > On Apr 10, 4:46 pm, Duncan Booth wrote: >> vsoler wrote: >> > I get the following error message: >> >> > TypeError: m() takes no arguments (1 given) >> >> Which version of Python are you using? Python 2.6 gives: >> >> TypeError: unbound method m() must be called with Uno instance as first >> argument (got nothing instead) >> > Hello Duncan, > > Your error message is correct if you use class Uno(object): > However, the error message is different underclass Uno: > Odd. That's not what I get: Python 2.6.1 (r26:67517, Dec 4 2008, 16:59:09) [MSC v.1500 64 bit (AMD64)] on win32 Type "copyright", "credits" or "license()" for more information. Personal firewall software may warn about the connection IDLE makes to its subprocess using this computer's internal loopback interface. This connection is not visible on any external interface and no data is sent to or received from the Internet. IDLE 2.6.1 >>> class Uno: a=1 def m(): print "mouse" >>> Uno.m() Traceback (most recent call last): File "", line 1, in Uno.m() TypeError: unbound method m() must be called with Uno instance as first argument (got nothing instead) >>> Anyway, the moral is never, ever to use old-style classes in Python 2.x. You will get weird and unexpected results. -- http://mail.python.org/mailman/listinfo/python-list
Re: Python and Regular Expressions
On 2010-04-10, Patrick Maupin wrote: > Trust me, I already knew that. But what you just wrote is a > much more useful thing to tell the OP than "Every time someone > tries to parse nested structures using regular expressions, > Jamie Zawinski kills a puppy" which is what I was responding > to. And right after regurgitating that inside joke, Chris > Rebert then went on to say "Try using an *actual* parser, such > as Pyparsing". Which is all well and good, except then the OP > will download pyparsing, take a look, realize that it uses > regexps under the hood, and possibly be very confused. I don't agree with that. If a person is trying to ski using pieces of wood that they carved themselves, I don't expect them to be surprised that the skis they buy are made out of similar materials. -- Neil Cerutti -- http://mail.python.org/mailman/listinfo/python-list
"KARACHI UNIVERSITY Centers of BSc (Pass) 1st/2nd year Computer Science Practical Examination 2009" "KARACHI UNIVERSITY DATE SHEET B.COM" "BA / B.SC" "MA / M.SC" "FA / F.SC." "METRIC" "BOARD" ON http
"KARACHI UNIVERSITY Centers of BSc (Pass) 1st/2nd year Computer Science Practical Examination 2009" "KARACHI UNIVERSITY DATE SHEET B.COM" "BA / B.SC" "MA / M.SC" "FA / F.SC." "METRIC" "BOARD" ON http://interface-edu-pk.blogspot.com/ "KARACHI UNIVERSITY Centers of BSc (Pass) 1st/2nd year Computer Science Practical Examination 2009" "KARACHI UNIVERSITY DATE SHEET B.COM" "BA / B.SC" "MA / M.SC" "FA / F.SC." "METRIC" "BOARD" ON http://interface-edu-pk.blogspot.com/ "KARACHI UNIVERSITY Centers of BSc (Pass) 1st/2nd year Computer Science Practical Examination 2009" "KARACHI UNIVERSITY DATE SHEET B.COM" "BA / B.SC" "MA / M.SC" "FA / F.SC." "METRIC" "BOARD" ON http://interface-edu-pk.blogspot.com/ "KARACHI UNIVERSITY Centers of BSc (Pass) 1st/2nd year Computer Science Practical Examination 2009" "KARACHI UNIVERSITY DATE SHEET B.COM" "BA / B.SC" "MA / M.SC" "FA / F.SC." "METRIC" "BOARD" ON http://interface-edu-pk.blogspot.com/ "KARACHI UNIVERSITY Centers of BSc (Pass) 1st/2nd year Computer Science Practical Examination 2009" "KARACHI UNIVERSITY DATE SHEET B.COM" "BA / B.SC" "MA / M.SC" "FA / F.SC." "METRIC" "BOARD" ON http://interface-edu-pk.blogspot.com/ "KARACHI UNIVERSITY Centers of BSc (Pass) 1st/2nd year Computer Science Practical Examination 2009" "KARACHI UNIVERSITY DATE SHEET B.COM" "BA / B.SC" "MA / M.SC" "FA / F.SC." "METRIC" "BOARD" ON http://interface-edu-pk.blogspot.com/ "KARACHI UNIVERSITY Centers of BSc (Pass) 1st/2nd year Computer Science Practical Examination 2009" "KARACHI UNIVERSITY DATE SHEET B.COM" "BA / B.SC" "MA / M.SC" "FA / F.SC." "METRIC" "BOARD" ON http://interface-edu-pk.blogspot.com/ "KARACHI UNIVERSITY Centers of BSc (Pass) 1st/2nd year Computer Science Practical Examination 2009" "KARACHI UNIVERSITY DATE SHEET B.COM" "BA / B.SC" "MA / M.SC" "FA / F.SC." "METRIC" "BOARD" ON http://interface-edu-pk.blogspot.com/ "KARACHI UNIVERSITY Centers of BSc (Pass) 1st/2nd year Computer Science Practical Examination 2009" "KARACHI UNIVERSITY DATE SHEET B.COM" "BA / B.SC" "MA / M.SC" "FA / F.SC." "METRIC" "BOARD" ON http://interface-edu-pk.blogspot.com/ "KARACHI UNIVERSITY Centers of BSc (Pass) 1st/2nd year Computer Science Practical Examination 2009" "KARACHI UNIVERSITY DATE SHEET B.COM" "BA / B.SC" "MA / M.SC" "FA / F.SC." "METRIC" "BOARD" ON http://interface-edu-pk.blogspot.com/ "KARACHI UNIVERSITY Centers of BSc (Pass) 1st/2nd year Computer Science Practical Examination 2009" "KARACHI UNIVERSITY DATE SHEET B.COM" "BA / B.SC" "MA / M.SC" "FA / F.SC." "METRIC" "BOARD" ON http://interface-edu-pk.blogspot.com/ "KARACHI UNIVERSITY Centers of BSc (Pass) 1st/2nd year Computer Science Practical Examination 2009" "KARACHI UNIVERSITY DATE SHEET B.COM" "BA / B.SC" "MA / M.SC" "FA / F.SC." "METRIC" "BOARD" ON http://interface-edu-pk.blogspot.com/ "KARACHI UNIVERSITY Centers of BSc (Pass) 1st/2nd year Computer Science Practical Examination 2009" "KARACHI UNIVERSITY DATE SHEET B.COM" "BA / B.SC" "MA / M.SC" "FA / F.SC." "METRIC" "BOARD" ON http://interface-edu-pk.blogspot.com/ "KARACHI UNIVERSITY Centers of BSc (Pass) 1st/2nd year Computer Science Practical Examination 2009" "KARACHI UNIVERSITY DATE SHEET B.COM" "BA / B.SC" "MA / M.SC" "FA / F.SC." "METRIC" "BOARD" ON http://interface-edu-pk.blogspot.com/ "KARACHI UNIVERSITY Centers of BSc (Pass) 1st/2nd year Computer Science Practical Examination 2009" "KARACHI UNIVERSITY DATE SHEET B.COM" "BA / B.SC" "MA / M.SC" "FA / F.SC." "METRIC" "BOARD" ON http://interface-edu-pk.blogspot.com/ "KARACHI UNIVERSITY Centers of BSc (Pass) 1st/2nd year Computer Science Practical Examination 2009" "KARACHI UNIVERSITY DATE SHEET B.COM" "BA / B.SC" "MA / M.SC" "FA / F.SC." "METRIC" "BOARD" ON http://interface-edu-pk.blogspot.com/ "KARACHI UNIVERSITY Centers of BSc (Pass) 1st/2nd year Computer Science Practical Examination 2009" "KARACHI UNIVERSITY DATE SHEET B.COM" "BA / B.SC" "MA / M.SC" "FA / F.SC." "METRIC" "BOARD" ON http://interface-edu-pk.blogspot.com/ "KARACHI UNIVERSITY Centers of BSc (Pass) 1st/2nd year Computer Science Practical Examination 2009" "KARACHI UNIVERSITY DATE SHEET B.COM" "BA / B.SC" "MA / M.SC" "FA / F.SC." "METRIC" "BOARD" ON http://interface-edu-pk.blogspot.com/ "KARACHI UNIVERSITY Centers of BSc (Pass) 1st/2nd year Computer Science Practical Examination 2009" "KARACHI UNIVERSITY DATE SHEET B.COM" "BA / B.SC" "MA / M.SC" "FA / F.SC." "METRIC" "BOARD" ON http://interface-edu-pk.blogspot.com/ "KARACHI UNIVERSITY Centers of BSc (Pass) 1st/2nd year Computer Science Practical Examination 2009" "KARACHI UNIVERSITY DATE SHEET B.COM" "BA / B.SC" "MA / M.SC" "FA / F.SC." "METRIC" "BOARD" ON http://interface-edu-pk.blogspot.com/ "KARACHI UNIVERSITY Centers of BSc (Pass) 1st/2nd year Computer Science Practical Examination 2009" "KARACHI UNIVERSITY DATE SHEET B.COM" "BA / B.SC" "MA / M.SC" "FA / F.SC." "ME
Re: Cleanup guarantees?
* Gabriel Genellina: En Fri, 09 Apr 2010 01:13:37 -0300, Alf P. Steinbach escribió: > > import urllib.request # urlopen > import codecs # getreader > import sys # stderr > > def text_stream_from( url, encoding ): > text_reader = codecs.getreader( encoding ) > connection = urllib.request.urlopen( url ) > return text_reader( connection ) > > def list_text( url, encoding ): > lines = text_stream_from( url, encoding ) > for line in lines: > print( line, end = "" ) > lines.close() # Undocumented? > > url = "http://www.rfc-editor.org/rfc/rfc1149.txt"; > list_text( url, "ascii" ) > > > First, I'm unable to find documentation that there /is/ a close method in the > text_reader object, and I'm unable to find documentation that there is a close > method in the file like connection object; is there such documentation? codecs.getreader returns a StreamReader instance (see [1]) StreamReader is documented here [2] and it says "In addition to the above methods, the StreamReader must also inherit all other methods and attributes from the underlying stream." -- the stream being 'connection', from urllib.request.urlopen. The 3.x version of the documentation in [3] doesn't provide any details except being "a file-like object". The 2.x version [4] is much more clear: "a file-like object is returned. This supports the following methods: read(), readline(), readlines(), fileno(), close(), info(), getcode() and geturl(). It also has proper support for the iterator protocol." [1] http://docs.python.org/py3k/library/codecs.html#codecs.getreader [2] http://docs.python.org/py3k/library/codecs.html#codecs.StreamReader [3] http://docs.python.org/py3k/library/urllib.request.html#urllib.request.urlopen [4] http://docs.python.org/library/urllib.html#urllib.urlopen Thanks. > Second, I'm unable to find documentation of when they're called and what they > do. It seems that (A) when the connection object's st method is called automatically, and (B) that when the > text_reader object's close method is called it calls the close method of the > wrapped stream (i.e. on the connection object). But where is this documented? Nowhere, AFAIK. I bet documentation patches are welcome. Well, I think I know too little about intentions to do any documentation patches. Cheers, - Alf -- http://mail.python.org/mailman/listinfo/python-list
file events using fsevents for mac
Hi Everyone, I m using python3 for my application and i need to capture file events using fsevents. Is ter anyone knows to access fsevents in python3. thanks for help in advance rgds mathan -- http://mail.python.org/mailman/listinfo/python-list
Re: Python and Regular Expressions
On Apr 10, 11:35 am, Neil Cerutti wrote: > On 2010-04-10, Patrick Maupin wrote: > > as Pyparsing". Which is all well and good, except then the OP > > will download pyparsing, take a look, realize that it uses > > regexps under the hood, and possibly be very confused. > > I don't agree with that. If a person is trying to ski using > pieces of wood that they carved themselves, I don't expect them > to be surprised that the skis they buy are made out of similar > materials. But, in this case, the guy ASKED how to make the skis in his woodworking shop, and was told not to be silly -- you don't use wood to make skis -- and then directed to go buy some skis that are, in fact, made out of wood. I think it would have been perfectly appropriate to point out that it might take some additional woodworking equipment and a bit of experience and/or study and/or extra work to make decent skis out of wood (and, oh, by the way, here is where you can buy some ready-made skis cheap), but the original response didn't explain it like this. Regards, Pat -- http://mail.python.org/mailman/listinfo/python-list
Re: Automatic import ?
In article <4bac361d$0$8840$c3e8...@news.astraweb.com>, Steven D'Aprano wrote: >On Thu, 25 Mar 2010 18:03:58 -0700, C. B. wrote: >> >> from mymodule import AAA >> from mymodule import BBB >> >> a = AAA(BBB())) >> >> But, as there is no case where AAA can be used without BBB, I would like >> to avoid importing BBB in my Python scripts when I already import AAA. > >Since AAA must take an argument of BBB, then give it a default: > ># in mymodule >def AAA(arg=BBB()): >... That would frequently give wrong results unless BBB is explicitly designed to create immutable instances. I strongly suggest doing the usual mutable dance: def AAA(arg=None): if arg is None: arg = BBB() -- Aahz (a...@pythoncraft.com) <*> http://www.pythoncraft.com/ "It is easier to optimize correct code than to correct optimized code." --Bill Harlan -- http://mail.python.org/mailman/listinfo/python-list
Re: Classes as namespaces?
In article , kj wrote: > >What's the word on using "classes as namespaces"? E.g. > >class _cfg(object): >spam = 1 >jambon = 3 >huevos = 2 > >breakfast = (_cfg.spam, _cfg.jambon, _cfg.huevos) There is one gotcha associated with using classes as namespaces: you have to be careful to avoid instantiating them. That goes triple if you modify the class attributes, because modifying an attribute in an instance does *not* propagate the change to the class. -- Aahz (a...@pythoncraft.com) <*> http://www.pythoncraft.com/ "It is easier to optimize correct code than to correct optimized code." --Bill Harlan -- http://mail.python.org/mailman/listinfo/python-list
Re: Python and Regular Expressions
Patrick Maupin, 10.04.2010 19:11: On Apr 10, 11:35 am, Neil Cerutti wrote: On 2010-04-10, Patrick Maupin wrote: as Pyparsing". Which is all well and good, except then the OP will download pyparsing, take a look, realize that it uses regexps under the hood, and possibly be very confused. I don't agree with that. If a person is trying to ski using pieces of wood that they carved themselves, I don't expect them to be surprised that the skis they buy are made out of similar materials. But, in this case, the guy ASKED how to make the skis in his woodworking shop, and was told not to be silly -- you don't use wood to make skis -- and then directed to go buy some skis that are, in fact, made out of wood. Running a Python program in CPython eventually boils down to a sequence of commands being executed by the CPU. That doesn't mean you should write those commands manually, even if you can. It's perfectly ok to write the program in Python instead. Stefan -- http://mail.python.org/mailman/listinfo/python-list
[RELEASED] 2.7 beta 1
On behalf of the Python development team, I'm merry to announce the first beta release of Python 2.7. Python 2.7 is scheduled (by Guido and Python-dev) to be the last major version in the 2.x series. Though more major releases have not been absolutely ruled out, it's likely that the 2.7 release will an extended period of maintenance for the 2.x series. 2.7 includes many features that were first released in Python 3.1. The faster io module, the new nested with statement syntax, improved float repr, set literals, dictionary views, and the memoryview object have been backported from 3.1. Other features include an ordered dictionary implementation, unittests improvements, a new sysconfig module, and support for ttk Tile in Tkinter. For a more extensive list of changes in 2.7, see http://doc.python.org/dev/whatsnew/2.7.html or Misc/NEWS in the Python distribution. To download Python 2.7 visit: http://www.python.org/download/releases/2.7/ While this is a development release and is thus not suitable for production use, we encourage Python application and library developers to test the release with their code and report any bugs they encounter. The 2.7 documentation can be found at: http://docs.python.org/2.7 Please consider trying Python 2.7 with your code and reporting any bugs you may notice to: http://bugs.python.org Enjoy! -- Benjamin Peterson 2.7 Release Manager benjamin at python.org (on behalf of the entire python-dev team and 2.7's contributors) -- http://mail.python.org/mailman/listinfo/python-list
Re: Tempering Client Expectations (OT)
On 04/10/2010 11:10 AM, Victor Subervi wrote: Hi; I'm working with my first client where I've developed a custom script. I way underbid the project and I ate that as part of my learning experience. We outlined as precisely as I knew how what functionality was needed. Then he went to input data and lo and behold he needed more functionality. I told him that would require more investment. This went on a few times and now he's hopping mad about being nickeled and dimed to death. hahahaha...shocked, I say, shocked! okay...with that out of the way... Any good articles out there (or other advice) on how to deal with a situation like this? Given your track record, I'm not sure that even if folks here offer advice, you'll heed it. But here goes: 1) Preeminently, address second-order ignorance. Learn about the involved technologies before you consider proposing a solution. Had you taken the time up-front to ask any competent web developer "I'd like to make a web-application from scratch, what do I need to know?" they'd tell you to learn HTTP, HTML, CSS, Javascript, a server-side scripting language such as Python/PHP/Perl/Ruby, database/SQL technologies, and security best-practices (or they might question why you don't reuse an existing framework that already does what you want). There are plenty of books & websites to facilitate learning *all* of these topics. GIYF. That list alone might have given you pause enough to say "woah, that's a lot, and all I know is a little HTML. Maybe the task of being a web programmer isn't as easy as I thought." But, in the face of the daunting mountain of requisite skills, you opt to proceed... 2) Next, address first-order ignorance: learn the requisite technologies involved in such a project. Learn HTML, CSS, Javascript, how an HTTP transaction works, how to program well in your chosen scripting language, how to write SQL, and how to identify common security issues (OWASP puts out a good list). This doesn't preclude you from doing paid projects for friends as you learn, but keep the funding down in the "buy me lunch and I'll tinker with your idea" range, not in the "pay me real money for a real application" range. Make sure that the friend knows your level of experience (or lack thereof) doing what they want. And don't fudge it with "I wrote this other web application" eliding the fact that said-web-app blew up in your face. Be honest. All artists need to master their tools, whether words, pigments, clay, or technologies. 3) When multiple professional-programmers on comp.lang.python face-palm and suggest you're doing something wrong or you lack an understanding, try listening and spending time to wrap your head around what they're saying. Instead of dismissing with "I'm an artist, I can't understand that", STOP. Let you client know you just stepped off the deep end, and suspend the project. Hire somebody who does understand or take a class (this may cost real money). But don't try and proceed in the face as your own non-understanding without first coming to terms with the issue. 4) Don't be afraid to reuse existing technologies: could installing osCommerce on a $3/month web-server and tweaking the PHP code have sufficed for what you need? Could you have used Django+Satchmo to get yourself up and running with proven code, tweaking what you need? I remember you dismissing the suggestion to use existing web-frameworks. 5) Regarding scope-creep, it's a problem most developers & analysts face, but there are several mitigating methods you can use. Experience from past projects helps gauge time for future projects and only your own experience will suffice. If you don't have any past projects (personal deployments or school projects) you're not yet remotely ready to give estimates. Even after you've done multiple projects, estimation is still as much an art as a science. Also, get the client to sign off on basic features in very small bite-sized increments, addressing highest-priority needs first. If at any time the client sees a failure to progress at the rate they expect, they can pull the plug losing far less of their investment keeping the most important features developed thus-far. Part of a developer/analyst's job is to get a good idea of a project's scope. Examining all edge cases, looking for infrequently-used processes, probing exceptions, building a mental-model that corresponds to the client's mental-model... 6) As for "Tempering Client Expectations" (the subject line of this OT post), it seems the biggest gap involved not communicating to your client/friend "I'm using your project as a learning experience for multiple complicated technologies and I have minimal idea what is involved so there's no possible way I could give you an accurate estimate of scope or cost" -tkc -- http://mail.python.org/mailman/listinfo/python-list
bps coordinate identification
Dear all, Given a gps coordinate, I would like to find out the country the coordinate belongs to. I wonder whether there is a python library that offers this capability... Thanks in advance for any pointer. Cheers, Luis PS: I am already aware of basemap but it seems we cannot answer this type of query with it. -- http://mail.python.org/mailman/listinfo/python-list
Re: The Regex Story
> Unreasonable phobia to regex is just as much harmful as overuse of it. > Agreed. I did not mean to sound as if I am against the use of regular expressions. -- Dotan Cohen http://bido.com http://what-is-what.com -- http://mail.python.org/mailman/listinfo/python-list
Re: ANN: obfuscate 0.2.2
Steven D'Aprano writes: > DISCLAIMER: obfuscate is not cryptographically strong, and should not be > used where high security is required. Certainly no one should never use obfuscate's rot13 function for high security. Use at least double-rot13 instead, or maybe even quadruple rot13 ;-). -- http://mail.python.org/mailman/listinfo/python-list
Re: [Python-Dev] [RELEASED] 2.7 beta 1
> On behalf of the Python development team, I'm merry to announce the first beta > release of Python 2.7. > > Python 2.7 is scheduled (by Guido and Python-dev) to be the last major version > in the 2.x series. Though more major releases have not been absolutely ruled > out, it's likely that the 2.7 release will an extended period of maintenance > for > the 2.x series. May I propose that the developers consider keeping this release *beta* until after the present Python moratorium? That is, don't let it be marked as *official* until after, say, Python 3.3. There are so many features taken from 3.0 that I fear that it will postpone its adoption interminably (it is, in practice, treated as "beta" software itself). By making it doctrine that it won't be official until the next "major" Python release, it will encourage those who are able, to just make the jump to 3.0, while those who cannot will have the subtle pressure to make the shift, however gradual. Additionally, it will give the community further incentive to make Python3 all that it was intended to be. Personally, the timing of v3 prevented me from fully participating in that effort, and, not ignoring the work of those who did contribute, I think many of us feel that it has not reached its potential. Just a small suggestion... .. . marcos -- http://mail.python.org/mailman/listinfo/python-list
Re: [Python-Dev] [RELEASED] 2.7 beta 1
On Sat, Apr 10, 2010 at 4:13 PM, average wrote: > > On behalf of the Python development team, I'm merry to announce the first > beta > > release of Python 2.7. > > > > Python 2.7 is scheduled (by Guido and Python-dev) to be the last major > version > > in the 2.x series. Though more major releases have not been absolutely > ruled > > out, it's likely that the 2.7 release will an extended period of > maintenance for > > the 2.x series. > > May I propose that the developers consider keeping this release *beta* > until after the present Python moratorium? That is, don't let it be > marked as *official* until after, say, Python 3.3. > > There are so many features taken from 3.0 that I fear that it will > postpone its adoption interminably (it is, in practice, treated as > "beta" software itself). By making it doctrine that it won't be > official until the next "major" Python release, it will encourage > those who are able, to just make the jump to 3.0, while those who > cannot will have the subtle pressure to make the shift, however > gradual. Additionally, it will give the community further incentive > to make Python3 all that it was intended to be. Personally, the > timing of v3 prevented me from fully participating in that effort, > and, not ignoring the work of those who did contribute, I think many > of us feel that it has not reached its potential. > > Just a small suggestion... .. . > > marcos > -- > http://mail.python.org/mailman/listinfo/python-list > I disagree. 2.7 should go GA as soon as the developers deemed it stable. Those who don't need 3rd party packages will no doubt migrate to 3.x. Those that required 3rd party packages not yet ported to 3.x will want to use 2.7. Delaying 2.7 from GA doesn't change the reality. I myself would want to use back ported features from 2.7 as a way to prepare for migration as soon as those 3rd party packages are ported to 3.x. Mel -- http://mail.python.org/mailman/listinfo/python-list
Re: [Python-Dev] [RELEASED] 2.7 beta 1
average wrote: >> On behalf of the Python development team, I'm merry to announce the first >> beta >> release of Python 2.7. >> >> Python 2.7 is scheduled (by Guido and Python-dev) to be the last major >> version >> in the 2.x series. Though more major releases have not been absolutely ruled >> out, it's likely that the 2.7 release will an extended period of maintenance >> for >> the 2.x series. > > May I propose that the developers consider keeping this release *beta* > until after the present Python moratorium? That is, don't let it be > marked as *official* until after, say, Python 3.3. > > There are so many features taken from 3.0 that I fear that it will > postpone its adoption interminably Whether 3.x is adopted by developers is IMO not influenced by the 2.7 release schedule. At least the effect is highly speculative. So please simply release 2.7 when it's ready. Ciao, Michael. -- http://mail.python.org/mailman/listinfo/python-list
Re: [RELEASED] 2.7 beta 1
On Apr 10, 5:45 pm, Michael Ströder wrote: > average wrote: > >> On behalf of the Python development team, I'm merry to announce the first > >> beta > >> release of Python 2.7. > > >> Python 2.7 is scheduled (by Guido and Python-dev) to be the last major > >> version > >> in the 2.x series. Though more major releases have not been absolutely > >> ruled > >> out, it's likely that the 2.7 release will an extended period of > >> maintenance for > >> the 2.x series. > > > May I propose that the developers consider keeping this release *beta* > > until after the present Python moratorium? That is, don't let it be > > marked as *official* until after, say, Python 3.3. > > > There are so many features taken from 3.0 that I fear that it will > > postpone its adoption interminably > > Whether 3.x is adopted by developers is IMO not influenced by the 2.7 release > schedule. At least the effect is highly speculative. So please simply release > 2.7 when it's ready. 3.x won't be adopted by developers until it's fixed. As of now, it's seriously broken and unsuitable for production. > > Ciao, Michael. -- http://mail.python.org/mailman/listinfo/python-list
Re: [RELEASED] 2.7 beta 1
On Sat, Apr 10, 2010 at 4:47 PM, Mensanator wrote: > On Apr 10, 5:45 pm, Michael Ströder wrote: >> average wrote: >> >> On behalf of the Python development team, I'm merry to announce the first >> >> beta >> >> release of Python 2.7. >> >> >> Python 2.7 is scheduled (by Guido and Python-dev) to be the last major >> >> version >> >> in the 2.x series. Though more major releases have not been absolutely >> >> ruled >> >> out, it's likely that the 2.7 release will an extended period of >> >> maintenance for >> >> the 2.x series. >> >> > May I propose that the developers consider keeping this release *beta* >> > until after the present Python moratorium? That is, don't let it be >> > marked as *official* until after, say, Python 3.3. >> >> > There are so many features taken from 3.0 that I fear that it will >> > postpone its adoption interminably >> >> Whether 3.x is adopted by developers is IMO not influenced by the 2.7 release >> schedule. At least the effect is highly speculative. So please simply release >> 2.7 when it's ready. > > 3.x won't be adopted by developers until it's fixed. As of now, it's > seriously broken and unsuitable for production. In what ways do you consider it broken? Cheers, Chris -- http://mail.python.org/mailman/listinfo/python-list
Re: Python and Regular Expressions
Stefan Behnel wrote: Patrick Maupin, 10.04.2010 19:11: On Apr 10, 11:35 am, Neil Cerutti wrote: On 2010-04-10, Patrick Maupin wrote: as Pyparsing". Which is all well and good, except then the OP will download pyparsing, take a look, realize that it uses regexps under the hood, and possibly be very confused. I don't agree with that. If a person is trying to ski using pieces of wood that they carved themselves, I don't expect them to be surprised that the skis they buy are made out of similar materials. But, in this case, the guy ASKED how to make the skis in his woodworking shop, and was told not to be silly -- you don't use wood to make skis -- and then directed to go buy some skis that are, in fact, made out of wood. Running a Python program in CPython eventually boils down to a sequence of commands being executed by the CPU. That doesn't mean you should write those commands manually, even if you can. It's perfectly ok to write the program in Python instead. Stefan And it's even more perfectly okay to use Python when it's the best tool for the job, and re when *it's* the best tool for the job. ~Ethan~ -- http://mail.python.org/mailman/listinfo/python-list
Re: On Class namespaces, calling methods
On Sat, 10 Apr 2010 16:35:29 +, Duncan Booth wrote:
> Anyway, the moral is never, ever to use old-style classes in Python 2.x.
> You will get weird and unexpected results.
That's a bit strong. They're only weird and unexpected if you're not
expecting them and don't understand them.
Why are we worrying about the exact error message? New style or old
style, they both raise TypeError, and testing for the exact error message
is a fragile, dangerous thing to do: error strings are not part of the
Python API, and are subject to change without notice, for any reason. For
all we know, Python runtimes compiled on a Tuesday could use different
error messages from runtimes compiled on Wednesdays.
I can only think of two circumstances where old-style classes are
*wrong*: if you use multiple inheritance with a diamond diagram ("...now
you have THREE problems" *wink*), if you intend using descriptors such as
properties, or if you need __slots__. That's three circumstances:
multiple inheritance with a diamond diagram, descriptors, __slots__, and
__getattribute__. Four circumstances.
Any other time, they're merely discouraged, and gone in Python 3.x.
--
Steven
--
http://mail.python.org/mailman/listinfo/python-list
Re: ANN: obfuscate 0.2.2
On Sat, 10 Apr 2010 13:34:17 -0700, Paul Rubin wrote: > Steven D'Aprano writes: >> DISCLAIMER: obfuscate is not cryptographically strong, and should not >> be used where high security is required. > > Certainly no one should never use obfuscate's rot13 function for high > security. Use at least double-rot13 instead, or maybe even quadruple > rot13 ;-). Ha ha, that's funny! I've never heard that one before! *wink* I may add a quadruple-rot13 to the next release. Would you like credit? obfuscate does include ciphers which, prior to the invention of the computer, were good enough for real world use. E.g. the Playfair cipher was still in use for field communications in World War 2, e.g: http://practicalcryptography.com/ciphers/playfair-cipher/ and of course Vigenere is uncrackable if you provide it with a cryptographically random key as long as the message which you use only once. (In that case, it is a one-time-pad.) -- Steven -- http://mail.python.org/mailman/listinfo/python-list
Re: Python and Regular Expressions
On Sat, 10 Apr 2010 10:11:07 -0700, Patrick Maupin wrote: > On Apr 10, 11:35 am, Neil Cerutti wrote: >> On 2010-04-10, Patrick Maupin wrote: >> > as Pyparsing". Which is all well and good, except then the OP will >> > download pyparsing, take a look, realize that it uses regexps under >> > the hood, and possibly be very confused. >> >> I don't agree with that. If a person is trying to ski using pieces of >> wood that they carved themselves, I don't expect them to be surprised >> that the skis they buy are made out of similar materials. > > But, in this case, the guy ASKED how to make the skis in his woodworking > shop, and was told not to be silly -- you don't use wood to make skis -- > and then directed to go buy some skis that are, in fact, made out of > wood. As entertaining as this is, the analogy is rubbish. Skis are far too simple to use as an analogy for a parser (he says, having never seen skis up close in his life *wink*). Have you looked at PyParsing's source code? Regexes are only a small part of the parser, and not analogous to the wood of skis. Perhaps a better analogy would be a tennis racket, with regexes being the strings. You have a whole lot of strings, not just one, and they are held together with a strong framework. Without the framework the strings are useless, and without the strings the racket doesn't do anything useful. Using this analogy, I would say the OP was wanting to play tennis with a single piece of string, and asking for advise on beefing it up to make it work better. Perhaps a knot tied in one end will help? -- Steven -- http://mail.python.org/mailman/listinfo/python-list
Re: Performance of list vs. set equality operations
On 4/10/2010 8:32 AM, Stefan Behnel wrote: Steven D'Aprano, 08.04.2010 03:41: On Wed, 07 Apr 2010 10:55:10 -0700, Raymond Hettinger wrote: If the two collections have unequal sizes, then both ways immediately return unequal. Perhaps I'm misinterpreting what you are saying, but I can't confirm that behaviour, at least not for subclasses of list: >>> class MyList(list): ... def __len__(self): ... return self.n ... >>> L1 = MyList(range(10)) >>> L2 = MyList(range(10)) >>> L1.n = 9 >>> L2.n = 10 >>> L1 == L2 True >>> len(L1) == len(L2) False This code incorrectly assumes that overriding __len__ has an impact on the equality of two lists. If you want to influence the equality, you need to override __eq__. If you don't, the original implementation is free to do whatever it likes to determine if it is equal to another value or not. If it uses __len__ for that or not is only an implementation detail that can't be relied upon. After reading the responses of both you and Raymond, I realized that a) there is a real difference between 'checking lengths' and 'calling __len__', which I (and apparently the example) had seen as the same and b) that the example shows that assuming that they are the same is a mistake. Thank you both for the clarification. Terry Jan Reedy -- http://mail.python.org/mailman/listinfo/python-list
Re: Python and Regular Expressions
Steven D'Aprano writes: > As entertaining as this is, the analogy is rubbish. Skis are far too > simple to use as an analogy for a parser (he says, having never seen skis > up close in his life *wink*). Have you looked at PyParsing's source code? > Regexes are only a small part of the parser, and not analogous to the > wood of skis. The impression that I have (from a distance) is that Pyparsing is a good interface abstraction with a kludgy and slow implementation. That the implementation uses regexps just goes to show how kludgy it is. One hopes that someday there will be a more serious implementation, perhaps using llvm-py (I wonder whatever happened to that project, by the way) so that your parser script will compile to executable machine code on the fly. -- http://mail.python.org/mailman/listinfo/python-list
Re: ANN: obfuscate 0.2.2
On Sun, Apr 11, 2010 at 1:17 AM, Steven D'Aprano wrote: > On Sat, 10 Apr 2010 13:34:17 -0700, Paul Rubin wrote: > >> Steven D'Aprano writes: >>> DISCLAIMER: obfuscate is not cryptographically strong, and should not >>> be used where high security is required. >> >> Certainly no one should never use obfuscate's rot13 function for high >> security. Use at least double-rot13 instead, or maybe even quadruple >> rot13 ;-). > > Ha ha, that's funny! I've never heard that one before! *wink* I think I lost a sarcasm detector to this line- are you being serious? Geremy Condra -- http://mail.python.org/mailman/listinfo/python-list
doctest.testfile fails on text files with Windows line endings
After converting a text file containing doctests to use Windows line endings, I'm getting spurious errors: ValueError: line 19 of the docstring for examples.txt has inconsistent leading whitespace: '\r' I don't believe that doctest.testfile is documented as requiring Unix line endings, and the line endings in the file are okay. I've checked in a hex editor, and they are valid \r\n line endings. In doctest._load_testfile, I find this comment and code: # get_data() opens files as 'rb', so one must do the equivalent # conversion as universal newlines would do. return file_contents.replace(os.linesep, '\n'), filename which I read as an attempt to normalise line endings in the file to \n. (But surely this will fail? If you're running, say, Linux or MacOS, linesep will already be '\n' not '\r\n', and consequently the replace does nothing, any Windows line endings aren't normalised, and doctest will choke on the \r characters. It's only useful if running on Windows.) But the above only occurs when using a package loader. Otherwise, _load_testfile executes: return open(filename).read(), filename which doesn't do any line ending normalisation at all. To my mind, this is a bug in doctest. Does anyone disagree? I think the simplest fix is to change it to: return open(filename, 'rU').read(), filename Comments? -- Steven -- http://mail.python.org/mailman/listinfo/python-list
Re: ANN: obfuscate 0.2.2
On Sun, 11 Apr 2010 03:00:50 +, geremy condra wrote: > On Sun, Apr 11, 2010 at 1:17 AM, Steven D'Aprano > wrote: >> On Sat, 10 Apr 2010 13:34:17 -0700, Paul Rubin wrote: >> >>> Steven D'Aprano writes: DISCLAIMER: obfuscate is not cryptographically strong, and should not be used where high security is required. >>> >>> Certainly no one should never use obfuscate's rot13 function for high >>> security. Use at least double-rot13 instead, or maybe even quadruple >>> rot13 ;-). >> >> Ha ha, that's funny! I've never heard that one before! *wink* > > I think I lost a sarcasm detector to this line- are you being serious? Possibly I overloaded your sarcasm detector and broke it. No, I'm not serious. If I had a dollar for every time somebody suggested using rot13 twice for extra security, I could buy out Microsoft. Hell, if I had a dollar for every time *I* suggested using rot13 twice, I could buy out Google. -- Steven -- http://mail.python.org/mailman/listinfo/python-list
[Possibly OT] Comments on PyPI
How do I leave comments on PyPI? There's a checkbox "Allow comments on releases" which I have checked, but no obvious way to actually post a comment. There's a link on the sidebar called "Comments", but it goes to a page about the Catalog SIG. I know there was a push to remove comments from PyPI last year, but the poll came back (marginally) in favour of keeping them. http://old.nabble.com/Poll-results-td26597897.html -- Steven -- http://mail.python.org/mailman/listinfo/python-list
Re: daemon.DaemonContext and logging
Sean DiZazzo writes:
> I'm finally getting around to trying out the python-daemon module and
> have hit a wall. I'm trying to set up logging inside of the "with
> daemon.DaemonContext" block. But when I try to use a logger inside
> the block it throws an error:
Specifically, it's throwing an error because a logger set up *outside*
the context is no longer open *inside* the context.
[…]
> handler = logging.FileHandler("log.file")
> logger.addHandler(handler)
>
> pid = daemon.pidlockfile.TimeoutPIDLockFile("/var/run/daemontest.pid",
> 10)
>
> with daemon.DaemonContext(pidfile=pid, gid=0, uid=0,
> stdout=sys.stdout, stderr=sys.stderr):
> logger.info("POO")
Here, the daemon.DaemonContext has not been told to preserve the file
descriptor that was opened by ‘handler’; so that file descriptor gets
closed along with all the others when the DaemonContext opens.
Also, there's no point binding the ‘stdout’ and ‘stderr’ options to the
system streams as you've done: as the documentation specifies, becoming
a daemon process involves detaching from the controlling terminal, so
those streams will no longer be connected to anything.
If you want specific file descriptors to remain open, you need to tell
the DaemonContext which ones they are via the ‘files_preserve’ option:
#! /usr/bin/python
# -*- coding: utf-8; -*-
from __future__ import with_statement
import logging
import daemon
import daemon.pidlockfile
import sys
logger = logging.getLogger("DaemonLog")
logger.setLevel(logging.INFO)
formatter = logging.Formatter(
"%(asctime)s - %(name)s - %(levelname)s - %(message)s")
handler = logging.FileHandler("log.file")
logger.addHandler(handler)
pid = daemon.pidlockfile.TimeoutPIDLockFile(
"/tmp/dizazzo-daemontest.pid", 10)
daemon_context = daemon.DaemonContext(
pidfile=pid,
files_preserve=[handler.stream])
with daemon_context:
logger.info("POO")
Thanks for this question; it's now in the FAQ document for the next
version.
> Any advice? Also, I left in the call to TimeoutPIDLockfile() as well,
> because the library's documentation is pretty sparse, and I want to
> know if I'm using it properly.
Improvements to the documentation would be welcome, certainly.
--
\ “We now have access to so much information that we can find |
`\ support for any prejudice or opinion.” —David Suzuki, 2008-06-27 |
_o__) |
Ben Finney
--
http://mail.python.org/mailman/listinfo/python-list
Re: doctest.testfile fails on text files with Windows line endings
On Apr 10, 10:16 pm, Steven D'Aprano wrote:
> After converting a text file containing doctests to use Windows line
> endings, I'm getting spurious errors:
>
> ValueError: line 19 of the docstring for examples.txt has inconsistent
> leading whitespace: '\r'
>
> I don't believe that doctest.testfile is documented as requiring Unix
> line endings, and the line endings in the file are okay. I've checked in
> a hex editor, and they are valid \r\n line endings.
>
> In doctest._load_testfile, I find this comment and code:
>
> # get_data() opens files as 'rb', so one must do the equivalent
> # conversion as universal newlines would do.
> return file_contents.replace(os.linesep, '\n'), filename
>
> which I read as an attempt to normalise line endings in the file to \n.
>
> (But surely this will fail? If you're running, say, Linux or MacOS,
> linesep will already be '\n' not '\r\n', and consequently the replace
> does nothing, any Windows line endings aren't normalised, and doctest
> will choke on the \r characters. It's only useful if running on Windows.)
>
> But the above only occurs when using a package loader. Otherwise,
> _load_testfile executes:
>
> return open(filename).read(), filename
>
> which doesn't do any line ending normalisation at all.
>
> To my mind, this is a bug in doctest. Does anyone disagree? I think the
> simplest fix is to change it to:
>
> return open(filename, 'rU').read(), filename
>
> Comments?
>
> --
> Steven
Seems like a bug to me. I often assume that I don't know where a
string is coming from, so one of the first steps I usually take when
parsing a string is:
s = s.replace('\r\n', '\n').replace('\r', '\n')
And, out of long-standing pre-Python habit, I always open files in
binary mode and then have my way with them. I know universal mode is
available, but honestly, I don't care for all the bookkeeping on what
kinds of line endings have been seen -- I just want to normalize the
data.
Regards,
Pat
--
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Re: 2.7 beta 1
On Apr 10, 7:15�pm, Chris Rebert wrote: > On Sat, Apr 10, 2010 at 4:47 PM, Mensanator wrote: > > On Apr 10, 5:45�pm, Michael Str�der wrote: > >> average wrote: > >> >> On behalf of the Python development team, I'm merry to announce the > >> >> first beta > >> >> release of Python 2.7. > > >> >> Python 2.7 is scheduled (by Guido and Python-dev) to be the last major > >> >> version > >> >> in the 2.x series. �Though more major releases have not been absolutely > >> >> ruled > >> >> out, it's likely that the 2.7 release will an extended period of > >> >> maintenance for > >> >> the 2.x series. > > >> > May I propose that the developers consider keeping this release *beta* > >> > until after the present Python moratorium? �That is, don't let it be > >> > marked as *official* until after, say, Python 3.3. > > >> > There are so many features taken from 3.0 that I fear that it will > >> > postpone its adoption interminably > > >> Whether 3.x is adopted by developers is IMO not influenced by the 2.7 > >> release > >> schedule. At least the effect is highly speculative. So please simply > >> release > >> 2.7 when it's ready. > > > 3.x won't be adopted by developers until it's fixed. As of now, it's > > seriously broken and unsuitable for production. > > In what ways do you consider it broken? Issue 8093. Remarkably, this apparently hasn't been noticed before. I expect 2.7 will be around for a long time. > > Cheers, > Chris- Hide quoted text - > > - Show quoted text - -- http://mail.python.org/mailman/listinfo/python-list
SEC proposes the use of Python and XML
This week the SEC proposed new requirements for asset-backed securities that include the use of XML and Python: "The asset-level information would be provided according to proposed standards and in a tagged data format using eXtensible Markup Language (XML). In addition, we are proposing to require, along with the prospectus filing, the filing of a computer program of the contractual cash flow provisions expressed as downloadable source code in Python, a commonly used open source interpretive programming language." See: http://www.sec.gov/news/press/2010/2010-54.htm http://kelloggfinance.wordpress.com/2010/04/08/the-sec-gets-one-right Ted -- http://mail.python.org/mailman/listinfo/python-list
Re: Python and Regular Expressions
On Apr 10, 8:38 pm, Paul Rubin wrote: > The impression that I have (from a distance) is that Pyparsing is a good > interface abstraction with a kludgy and slow implementation. That the > implementation uses regexps just goes to show how kludgy it is. One > hopes that someday there will be a more serious implementation, perhaps > using llvm-py (I wonder whatever happened to that project, by the way) > so that your parser script will compile to executable machine code on > the fly. I am definitely flattered that pyparsing stirs up so much interest, and among such a distinguished group. But I have to take some umbrage at Paul Rubin's left-handed compliment, "Pyparsing is a good interface abstraction with a kludgy and slow implementation," especially since he forms his opinions "from a distance". I actually *did* put some thought into what I wanted in pyparsing before designing it, and this forms this chapter of "Getting Started with Pyparsing" (available here as a free online excerpt: http://my.safaribooksonline.com/9780596514235/what_makes_pyparsing_so_special#X2ludGVybmFsX0ZsYXNoUmVhZGVyP3htbGlkPTk3ODA1OTY1MTQyMzUvMTYmaW1hZ2VwYWdlPTE2), the "Zen of Pyparsing" as it were. My goals were: - build parsers using explicit constructs (such as words, groups, repetition, alternatives), vs. expression encoding using specialized character sequences, as found in regexen - easy parser construction from primitive elements to complex groups and alternatives, using Python's operator overloading for ease of direct implementation of parsers using ordinary Python syntax; include mechanisms for defining recursive parser expressions - implicit skipping of whitespace between parser elements - results returned not just as a list of strings, but as a rich data object, with access to parsed fields by name or by list index, taking interfaces from both dicts and lists for natural adoption into common Python idioms - no separate code-generation steps, a la lex/yacc - support for parse-time callbacks, for specialized token handling, conversion, and/or construction of data structures - 100% pure Python, to be runnable on any platform that supports Python - liberal licensing, to permit easy adoption into any user's projects anywhere So raw performance really didn't even make my short-list, beyond the obvious "should be tolerably fast enough." I have found myself reading posts on c.l.py with wording like "I'm trying to parse and I've been trying for hours/days to get this regex working." For kicks, I'd spend 5-15 minutes working up a working pyparsing solution, which *does* run comparatively slowly, perhaps taking a few minutes to process the poster's data file. But the net solution is developed and running in under 1/2 an hour, which to me seems like an overall gain compared to hours of fruitless struggling with backslashes and regex character sequences. On top of which, the pyparsing solutions are still readable when I come back to them weeks or months later, instead of staring at some line-noise regex and just scratch my head wondering what it was for. And sometimes "comparatively slowly" means that it runs 50x slower than a compiled method that runs in 0.02 seconds - that's still getting the job done in just 1 second. And is the internal use of regexes with pyparsing really a "kludge"? Why? They are almost completely hidden from the parser developer. And yet by using compiled regexes, I retain the portability of 100% Python while leveraging the compiled speed of the re engine. It does seem that there have been many posts of late (either on c.l.py or the related posts on Stackoverflow) where the OP is trying to either scrape content from HTML, or parse some type of recursive expression. HTML scrapers implemented using re's are terribly fragile, since HTML in the wild often contains little surprises (unexpected whitespace; upper/lower case inconsistencies; tag attributes in unpredictable order; attribute values with double, single, or no quotation marks) which completely frustrate any re-based approach. Granted, there are times when an re-parsing-of-HTML endeavor *isn't* futile or doomed from the start - the OP may be working with a very restricted set of HTML, generated from some other script so that the output is very consistent. Unfortunately, this poster usually gets thrown under the same "you'll never be able to parse HTML with re's" bus. I can't explain the surge in these posts, other than to wonder if we aren't just seeing a skewed sample - that is, the many cases where people *are* successfully using re's to solve their text extraction problems aren't getting posted to c.l.py, since no one posts questions they already have the answers to. So don't be too dismissive of pyparsing, Mr. Rubin. I've gotten many e- mails, wiki, and forum posts from Python users at all levels of the expertise scale, saying that pyparsing has helped them to be very productive in one or another aspect of creating a command parse
Re: ANN: obfuscate 0.2.2
In article , geremy condra wrote: >On Sun, Apr 11, 2010 at 1:17 AM, Steven D'Aprano > wrote: >> On Sat, 10 Apr 2010 13:34:17 -0700, Paul Rubin wrote: >>> Steven D'Aprano writes: DISCLAIMER: obfuscate is not cryptographically strong, and should not be used where high security is required. >>> >>> Certainly no one should never use obfuscate's rot13 function for high >>> security. Use at least double-rot13 instead, or maybe even quadruple >>> rot13 ;-). >> >> Ha ha, that's funny! I've never heard that one before! *wink* > >I think I lost a sarcasm detector to this line- are you being serious? There are people who have a .sig that says, "This message protected by double-rot13 for extra security." It's an extremely common jape. -- Aahz (a...@pythoncraft.com) <*> http://www.pythoncraft.com/ "It is easier to optimize correct code than to correct optimized code." --Bill Harlan -- http://mail.python.org/mailman/listinfo/python-list
Re: ANN: obfuscate 0.2.2
On Sun, Apr 11, 2010 at 3:44 AM, Steven D'Aprano wrote: > On Sun, 11 Apr 2010 03:00:50 +, geremy condra wrote: > >> On Sun, Apr 11, 2010 at 1:17 AM, Steven D'Aprano >> wrote: >>> On Sat, 10 Apr 2010 13:34:17 -0700, Paul Rubin wrote: >>> Steven D'Aprano writes: > DISCLAIMER: obfuscate is not cryptographically strong, and should not > be used where high security is required. Certainly no one should never use obfuscate's rot13 function for high security. Use at least double-rot13 instead, or maybe even quadruple rot13 ;-). >>> >>> Ha ha, that's funny! I've never heard that one before! *wink* >> >> I think I lost a sarcasm detector to this line- are you being serious? > > > Possibly I overloaded your sarcasm detector and broke it. I figured, but given how severely it broke I couldn't be sure. I suppose the fact that you used exclamation points should have tipped me off, though. Geremy Condra -- http://mail.python.org/mailman/listinfo/python-list
Re: ANN: obfuscate 0.2.2
On Sun, Apr 11, 2010 at 4:37 AM, Aahz wrote: > In article , > geremy condra wrote: >>On Sun, Apr 11, 2010 at 1:17 AM, Steven D'Aprano >> wrote: >>> On Sat, 10 Apr 2010 13:34:17 -0700, Paul Rubin wrote: Steven D'Aprano writes: > > DISCLAIMER: obfuscate is not cryptographically strong, and should not > be used where high security is required. Certainly no one should never use obfuscate's rot13 function for high security. Use at least double-rot13 instead, or maybe even quadruple rot13 ;-). >>> >>> Ha ha, that's funny! I've never heard that one before! *wink* >> >>I think I lost a sarcasm detector to this line- are you being serious? > > There are people who have a .sig that says, "This message protected by > double-rot13 for extra security." It's an extremely common jape. I work in infosec. I've heard it ;) Geremy Condra -- http://mail.python.org/mailman/listinfo/python-list
Re: 2.7 beta 1
Mensanator wrote: > 3.x won't be adopted by WINDOWS developers WHO USE IDLE until it's fixed. I think you left your hyperbole level too high so I turned it down for you. I don't know of _anyone_ who uses IDLE to run production code, nor do I follow how one errant IDE shows that Python 3.x as a language is broken. -- http://mail.python.org/mailman/listinfo/python-list
Error Occurs: Replace a character in a String
Hello, I am getting an error in my python script when I try to change
a character in a string. [b]But I dont know why or what to do to fix
it?[/b]
I have commented in my code where the error occurs
[code]
def format_file(filename):
HTML_file = open(filename,'r')
HTML_source = HTML_file.read()
HTML_file.close()
x = 0
# Format all ID's & classes correctly
temp_buf= HTML_source.lower()
class_occurence = temp_buf.count('class')
ID_occurence= temp_buf.count('id')
for n in range(class_occurence):
hit = temp_buf.find('class')
if not hit==-1:
temp_buf[hit] = '~' # Error: 'str' object does not support
item assignment
x = hit+5
# delete any spaces until we reach a letter or number
while xhttp://mail.python.org/mailman/listinfo/python-list
Re: Error Occurs: Replace a character in a String
On Sat, 10 Apr 2010 22:01:51 -0700, Jimbo wrote:
> Hello, I am getting an error in my python script when I try to change a
> character in a string. [b]But I dont know why or what to do to fix
> it?[/b]
>
> I have commented in my code where the error occurs
Generally speaking, posting the actual error (not retyping it from
memory, or summarising it, or eluding to something vaguely similar) is
recommended. In this case though, your error is simple enough that you
can get away without the full traceback:
> temp_buf[hit] = '~'
> # Error: 'str' object does not support item assignment
The error is exactly what it says: strings don't support item assignment.
Try this in an interactive session:
>>> s = 'abcd'
>>> s[1] = 'B'
Traceback (most recent call last):
File "", line 1, in
TypeError: 'str' object does not support item assignment
Just as it says: you can't assign to individual string items (characters).
This is because strings in Python are immutable -- once created, you
can't modify them. There are all sorts of reasons for this, which I won't
go into, but the consequence is that anytime you want to modify a string
you need to create a new one:
>>> s = s[0] + 'B' + s[2:]
>>> s
'aBcd'
But don't do the above! String concatenation is okay if you only do it
once or twice, but if you're doing a lot of it, your code will be
sloow. Best to avoid it whenever possible.
The best way to replace substrings is, not surprisingly, to use the
replace() method:
>>> print s.replace('B', '~')
a~cd
Or break the string up into a list of words:
words = mystring.split()
or a list of characters:
chars = list(mystring)
and operate on the list. Lists, unlike strings, are mutable and so you
can assign to items.
But I see you're trying to manually parse HTML. Have you considered using
the HTML parser that comes with Python?
--
Steven
--
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Re: SEC proposes the use of Python and XML
On Sat, Apr 10, 2010 at 9:13 PM, Ted Larson Freeman wrote: > This week the SEC proposed new requirements for asset-backed > securities that include the use of XML and Python: > > "The asset-level information would be provided according to proposed > standards and in a tagged data format using eXtensible Markup Language > (XML). In addition, we are proposing to require, along with the > prospectus filing, the filing of a computer program of the contractual > cash flow provisions expressed as downloadable source code in Python, > a commonly used open source interpretive programming language." I guess we've now gone from "executable pseudocode" to "executable legal code" :-) Cheers, Chris -- Cue the Perl jokes! http://blog.rebertia.com -- http://mail.python.org/mailman/listinfo/python-list
Re: Error Occurs: Replace a character in a String
On Apr 11, 12:01 am, Jimbo wrote:
> Hello, I am getting an error in my python script when I try to change
> a character in a string. [b]But I dont know why or what to do to fix
> it?[/b]
>
> I have commented in my code where the error occurs
>
> [code]
> def format_file(filename):
>
> HTML_file = open(filename,'r')
> HTML_source = HTML_file.read()
> HTML_file.close()
>
> x = 0
>
> # Format all ID's & classes correctly
> temp_buf = HTML_source.lower()
> class_occurence = temp_buf.count('class')
> ID_occurence = temp_buf.count('id')
>
> for n in range(class_occurence):
> hit = temp_buf.find('class')
> if not hit==-1:
> temp_buf[hit] = '~' # Error: 'str' object does not support
> item assignment
> x = hit+5
>
> # delete any spaces until we reach a letter or number
> while x if temp_buf[x] == ' ':
> tempbuf[x] = ''
> HTML_source[x] = ''
> elif temp_buf[x] == '=':
> pass
> #elif temp_buf[x] == "'" or temp_buf[x] == '"'
> isalpha(temp_buf[x])
> else:
> break
> x += 1
> [/code]
In Python, a string is an immutable (unchangeable) object.
You can convert a string into a list of characters (which is not
immutable:
mylist = list(temp_buf)
and then convert it back:
temp_buf = ''.join(mylist)
but you cannot do item assignments inside the string (and lists don't
have a find method, so you cannot use find on your list). You can
maintain a parallel list and string if you want (with the same
indices).
Also, not sure what you want to accomplish with this statement:
while xhttp://mail.python.org/mailman/listinfo/python-list
Re: SEC proposes the use of Python and XML
On Apr 10, 11:13 pm, Ted Larson Freeman wrote: > This week the SEC proposed new requirements for asset-backed > securities that include the use of XML and Python: > > "The asset-level information would be provided according to proposed > standards and in a tagged data format using eXtensible Markup Language > (XML). In addition, we are proposing to require, along with the > prospectus filing, the filing of a computer program of the contractual > cash flow provisions expressed as downloadable source code in Python, > a commonly used open source interpretive programming language." > > See:http://www.sec.gov/news/press/2010/2010-54.htmhttp://kelloggfinance.wordpress.com/2010/04/08/the-sec-gets-one-right > > Ted Now all we need is for the IRS to follow suit... -- http://mail.python.org/mailman/listinfo/python-list
Re: Python and Regular Expressions
On Apr 10, 1:05 pm, Stefan Behnel wrote: > Running a Python program in CPython eventually boils down to a sequence of > commands being executed by the CPU. That doesn't mean you should write > those commands manually, even if you can. It's perfectly ok to write the > program in Python instead. Absolutely. But (as I seem to have posted many times recently) if somebody asks how to do "x" it may be useful to point out that it sounds like he really wants "y" and there are already several canned solutions that do "y", but if he really wants "x", here is how he should do it, or here is why he will have problems if he attempts to do it (hint: whether Jamie Zawinski decides to kill a puppy or not is not really a problem for somebody just asking a programming question -- that's really up to Jamie). Regards, Pat -- http://mail.python.org/mailman/listinfo/python-list
