class versions and object deserialization
We have classes of this form classA version1, classA version2, classA version3 .. etc. This is same class that has been modified. Each "modification" creates a new version of a class. Each object has a version attribute which refers to the version of the class from which it was derived. egObjectA.version =1 # means it was derived from ClassA version1 Here is my problem. During object de-serializing, i would like to use the specific version of the class that was used to used to make the object. For example, if i am de-serializing object ObjectA withversion=3 then ClassA version 3 should be used. Source code for all the different variations of the classes is stored. This looks getting the object first the get the class. Any idea on how to approach this? -- *Mob UG: +256 (0) 70 1735800 | NL +31 (0) 6 852 841 38 | Gtalk: jmwebaze | skype: mwebazej | URL: www.astro.rug.nl/~jmwebaze /* Life runs on code */* -- http://mail.python.org/mailman/listinfo/python-list
Re: why () is () and [] is [] work in other way?
Am 24.04.2012 08:02 schrieb rusi: On Apr 23, 9:34 am, Steven D'Aprano wrote: "is" is never ill-defined. "is" always, without exception, returns True if the two operands are the same object, and False if they are not. This is literally the simplest operator in Python. Circular definition: In case you did not notice, 'is' and 'are' are (or is it is?) the same verb. Steven's definition tries not to define the "verb" "is", but it defines the meanung of the *operator* 'is'. He says that 'a is b' iff a and be are *the same objects*. We don't need to define the verb "to be", but the target of the definition is the entity "object" and its identity. Thomas -- http://mail.python.org/mailman/listinfo/python-list
Re: why () is () and [] is [] work in other way?
On 4/24/2012 8:02, rusi wrote: On Apr 23, 9:34 am, Steven D'Aprano wrote: "is" is never ill-defined. "is" always, without exception, returns True if the two operands are the same object, and False if they are not. This is literally the simplest operator in Python. Circular definition: In case you did not notice, 'is' and 'are' are (or is it is?) the same verb. Python is not English. Double-quoted 'is' is a Python operator, while non-quoted 'is' and 'are' are forms of the English verb 'to be'. If you change the name of the operator or the language in which you define the operator, you'll realize that there's no real circularity in that definition. Kiuhnm -- http://mail.python.org/mailman/listinfo/python-list
finding a regular expression in a file
Hello friends.
Newb question here.
I'm trying to find an efficient way to "grep" a file with python.
The problem is that all the solutions I find on the web read a line at a time
from the file with a "for line in" loop and check each line for the RE instead
of sweeping through the entire file.
This looks terribly inefficient...
I can read the entire file like so:
open("/etc/passwd").read()
and use that in an re.search - e.g:
re.search("root",open("/etc/passwd").read())
The above will work BUT it will not interpolate the "\n" as a newline and will
just print the entire file as a long line.
So if I try to look for '^root' (line starting with root) instead of 'root' it
will NOT work
any ideas on how to get around this?
Thanks.
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Re: finding a regular expression in a file
"S.B" writes:
> Hello friends.
>
> Newb question here.
> I'm trying to find an efficient way to "grep" a file with python.
> The problem is that all the solutions I find on the web read a line
> at a time from the file with a "for line in" loop and check each
> line for the RE instead of sweeping through the entire file.
> This looks terribly inefficient...
>
> I can read the entire file like so:
> open("/etc/passwd").read()
> and use that in an re.search - e.g:
> re.search("root",open("/etc/passwd").read())
> The above will work BUT it will not interpolate the "\n" as a
> newline and will just print the entire file as a long line.
> So if I try to look for '^root' (line starting with root) instead of
> 'root' it will NOT work
>
> any ideas on how to get around this?
Check MULTILINE mode in the documentation: ^ "Matches the start of the
string, and in MULTILINE mode also matches immediately after each
newline."
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Re: finding a regular expression in a file
On Apr 24, 2012 6:32 PM, "S.B" wrote:
>
> Hello friends.
>
> Newb question here.
> I'm trying to find an efficient way to "grep" a file with python.
> The problem is that all the solutions I find on the web read a line at a
time from the file with a "for line in" loop and check each line for the RE
instead of sweeping through the entire file.
> This looks terribly inefficient...
>
> I can read the entire file like so:
> open("/etc/passwd").read()
> and use that in an re.search - e.g:
> re.search("root",open("/etc/passwd").read())
> The above will work BUT it will not interpolate the "\n" as a newline and
will just print the entire file as a long line.
> So if I try to look for '^root' (line starting with root) instead of
'root' it will NOT work
>
> any ideas on how to get around this?
>
You want the re.MULTILINE flag.
http://docs.python.org/py3k/library/re.html#re.MULTILINE
--
Regards,
Kushal
--
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Re: why () is () and [] is [] work in other way?
On Apr 24, 4:06 pm, Thomas Rachel wrote: > Am 24.04.2012 08:02 schrieb rusi: > > > On Apr 23, 9:34 am, Steven D'Aprano > +comp.lang.pyt...@pearwood.info> wrote: > > >> "is" is never ill-defined. "is" always, without exception, returns True > >> if the two operands are the same object, and False if they are not. This > >> is literally the simplest operator in Python. > > > Circular definition: In case you did not notice, 'is' and 'are' are > > (or is it is?) the same verb. > > Steven's definition tries not to define the "verb" "is", but it defines > the meanung of the *operator* 'is'. > > He says that 'a is b' iff a and be are *the same objects*. We don't need > to define the verb "to be", but the target of the definition is the > entity "object" and its identity. Identity, sameness, equality and the verb to be are all about the same concept(s) and their definitions are *intrinsically* circular; see http://plato.stanford.edu/entries/identity/#2 And the seeming simplicity of the circular definitions hide the actual complexity of 'to be' for python: http://docs.python.org/reference/expressions.html#id26 (footnote 7) for math/philosophy: http://www.math.harvard.edu/~mazur/preprints/when_is_one.pdf -- http://mail.python.org/mailman/listinfo/python-list
Re: why () is () and [] is [] work in other way?
On 4/24/2012 15:25, rusi wrote:
On Apr 24, 4:06 pm, Thomas Rachel wrote:
Am 24.04.2012 08:02 schrieb rusi:
On Apr 23, 9:34 am, Steven D'Apranowrote:
"is" is never ill-defined. "is" always, without exception, returns True
if the two operands are the same object, and False if they are not. This
is literally the simplest operator in Python.
Circular definition: In case you did not notice, 'is' and 'are' are
(or is it is?) the same verb.
Steven's definition tries not to define the "verb" "is", but it defines
the meanung of the *operator* 'is'.
He says that 'a is b' iff a and be are *the same objects*. We don't need
to define the verb "to be", but the target of the definition is the
entity "object" and its identity.
Identity, sameness, equality and the verb to be are all about the same
concept(s) and their definitions are *intrinsically* circular; see
http://plato.stanford.edu/entries/identity/#2
And the seeming simplicity of the circular definitions hide the actual
complexity of 'to be'
for python: http://docs.python.org/reference/expressions.html#id26
(footnote 7)
for math/philosophy:
http://www.math.harvard.edu/~mazur/preprints/when_is_one.pdf
What you say is true in general, but not from an operational point of
view, especially if we restrict the set of objects whose sameness or
identity we want to check:
Let O be a set of tuples (id, data) where
{(id, data1), (id, data2)} subset O => data1 = data2
Def. (id1, data1) and (id2, data2) in O are /the same/ iff id1 = id2.
Now, it's easy to find a bijection between O and the set of Python's
objects which are in memory at any single point in time.
Anyway, you're being unnecessarily pedantic.
Kiuhnm
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Re: class versions and object deserialization
On Tue, Apr 24, 2012 at 1:02 AM, J. Mwebaze wrote: > We have classes of this form classA version1, classA version2, classA > version3 .. etc. This is same class that has been modified. Each > "modification" creates a new version of a class. Each object has a version > attribute which refers to the version of the class from which it was > derived. egObjectA.version =1 # means it was derived from ClassA version1 Note that each object already has a __class__ attribute containing the class it is an instance of, so unless you have special need of version number metadata, it may not be necessary. > Here is my problem. During object de-serializing, i would like to use the > specific version of the class that was used to used to make the object. For > example, if i am de-serializing object ObjectA withversion=3 then ClassA > version 3 should be used. Source code for all the different variations of > the classes is stored. What serialization scheme are you using, and how are the classes stored? If you're using pickle and you keep them accessible from the module they were defined in using the name they were defined with, then you won't need to do anything special here -- pickle will look up that name in that module and find the class. If you're doing something more creative, then you'll want to override the __reduce__ method in your classes to pass in a custom constructor that takes into account the version number. -- http://mail.python.org/mailman/listinfo/python-list
trying to use spec file
Hi I posted this yesterday to compiler-sig, but I'm not sure there is any traffic there? There is a rather complex spec file for making rpm of python interpreter, but I'm only seeing doc on making rpm packages (ie programs); and, the spec file has difficult errors. Is anyone interested in the spec file issues, or maybe I should just make a simple one from it? -George -- Forwarded message -- From: George Georgalis Date: Mon, Apr 23, 2012 at 6:18 PM Subject: trying to use spec file To: compiler-...@python.org Hi - hope this list is still active. I'd like to make an rpm of 2.7.3 with some path and release tweeks. However the spec file from the main distribution doesn't work for me and it has some numbers from the prior release at the top (2.6). -rw-r--r-- 1 1000 1002 13549 Apr 9 16:07 ./Python-2.7.3/Misc/RPM/python-2.7.spec Is it maintained? I would love some help and I can provide further details (strip stops with files not found); but first I'd like to confirm this file is working out of the box, for anyone? I'm invoking it with "rpmbuild -bb python-2.7.spec" and I have all the stated dependancies installed. Is this a supported path, it might be easier for me to just create a new spec file? -George -- George Georgalis, (415) 894-2710, http://www.galis.org/ -- George Georgalis, (415) 894-2710, http://www.galis.org/ -- http://mail.python.org/mailman/listinfo/python-list
Re: trying to use spec file
In article , George Georgalis wrote: > I posted this yesterday to compiler-sig, but I'm not sure there is any > traffic there? > > There is a rather complex spec file for making rpm of python > interpreter, but I'm only seeing doc on making rpm packages (ie > programs); and, the spec file has difficult errors. > > Is anyone interested in the spec file issues, or maybe I should just > make a simple one from it? I'm not sure why that spec file is still there. From the hg log for the spec file, it appears that it gets updated "automatically" at each release, likely by a script used by the release managers. But I'd be pretty surprised to find that anyone uses the spec files as released. The Python release process no longer produces RPMs (it looks like it did at some point in the distant past) so it would only be used downstream by third-party distributors who do but I'm guessing they have their own, more complex spec files that they maintain themselves. You might want to open an issue on the bug tracker (bugs.python.org) or ask on the python-dev mailing list. -- Ned Deily, n...@acm.org -- http://mail.python.org/mailman/listinfo/python-list
Re: from calendar import* doesn't import everything
On 04/24/12 18:18, Rotwang wrote: Sorry if this is a stupid question, but what is up with this: >>> from calendar import* >>> Calendar Traceback (most recent call last): File "", line 1, in Calendar NameError: name 'Calendar' is not defined >>> from calendar import Calendar >>> Calendar If you view the source, you can see that __all__ is declared without containing "Calendar" in it. So when you do "from calendar import *", only the things that are in __all__ are exported. Now the REASON why "Calendar" is absent from __all__ is a question for the developers of the module. But at least that's why Python is masking it from you. -tkc -- http://mail.python.org/mailman/listinfo/python-list
Re: from calendar import* doesn't import everything
On 4/25/2012 1:18, Rotwang wrote: > Sorry if this is a stupid question, but what is up with this: > > >>> from calendar import* > >>> Calendar > > Traceback (most recent call last): > File "", line 1, in > Calendar > NameError: name 'Calendar' is not defined > >>> from calendar import Calendar > >>> Calendar > > > ? calendar.py defines __all__ this way: __all__ = ["IllegalMonthError", "IllegalWeekdayError", "setfirstweekday", "firstweekday", "isleap", "leapdays", "weekday", "monthrange", "monthcalendar", "prmonth", "month", "prcal", "calendar", "timegm", "month_name", "month_abbr", "day_name", "day_abbr"] Only those names are imported with '*'. Kiuhnm -- http://mail.python.org/mailman/listinfo/python-list
Re: from calendar import* doesn't import everything
On 25/04/2012 00:42, Kiuhnm wrote: On 4/25/2012 1:18, Rotwang wrote: Sorry if this is a stupid question, but what is up with this: >>> from calendar import* >>> Calendar Traceback (most recent call last): File "", line 1, in Calendar NameError: name 'Calendar' is not defined >>> from calendar import Calendar >>> Calendar ? calendar.py defines __all__ this way: __all__ = ["IllegalMonthError", "IllegalWeekdayError", "setfirstweekday", "firstweekday", "isleap", "leapdays", "weekday", "monthrange", "monthcalendar", "prmonth", "month", "prcal", "calendar", "timegm", "month_name", "month_abbr", "day_name", "day_abbr"] Only those names are imported with '*'. Kiuhnm Oh, I didn't realise modules could do that. Thanks. Do you know what the rationale behind not including 'Calendar' is? -- Hate music? Then you'll hate this: http://tinyurl.com/psymix -- http://mail.python.org/mailman/listinfo/python-list
Re: from calendar import* doesn't import everything
see http://docs.python.org/tutorial/modules.html#importing-from-a-package http://stackoverflow.com/questions/2187583/whats-the-python-all-module-level-variable-for I know the 1st link is for importing from a package but the same applies for modules -- http://mail.python.org/mailman/listinfo/python-list
Re: from calendar import* doesn't import everything
On 4/25/2012 1:54, Rotwang wrote: On 25/04/2012 00:42, Kiuhnm wrote: On 4/25/2012 1:18, Rotwang wrote: Sorry if this is a stupid question, but what is up with this: >>> from calendar import* >>> Calendar Traceback (most recent call last): File "", line 1, in Calendar NameError: name 'Calendar' is not defined >>> from calendar import Calendar >>> Calendar ? calendar.py defines __all__ this way: __all__ = ["IllegalMonthError", "IllegalWeekdayError", "setfirstweekday", "firstweekday", "isleap", "leapdays", "weekday", "monthrange", "monthcalendar", "prmonth", "month", "prcal", "calendar", "timegm", "month_name", "month_abbr", "day_name", "day_abbr"] Only those names are imported with '*'. Kiuhnm Oh, I didn't realise modules could do that. Thanks. Do you know what the rationale behind not including 'Calendar' is? Let's see... at line 561 of calendar.py there's something suspicious: ---> # Support for old module level interface c = TextCalendar() firstweekday = c.getfirstweekday def setfirstweekday(firstweekday): try: firstweekday.__index__ except AttributeError: raise IllegalWeekdayError(firstweekday) if not MONDAY <= firstweekday <= SUNDAY: raise IllegalWeekdayError(firstweekday) c.firstweekday = firstweekday monthcalendar = c.monthdayscalendar prweek = c.prweek week = c.formatweek weekheader = c.formatweekheader prmonth = c.prmonth month = c.formatmonth calendar = c.formatyear prcal = c.pryear <--- So, it seems that "from calendar import *" is reserved for the "old interface" (i.e. non-OO). Kiuhnm -- http://mail.python.org/mailman/listinfo/python-list
generate random numbers in a deterministic way
Hi, I'm working with some sorting algorithms and I want to compare their efficiency. One test fills a list with one million random integers, which serves as input for the algorithms. However, if this list is different each time I run the tests, the tests wouldn't be fair. At the moment the selected sorting alg. can be specified with a switch and only one alg. is tested each time. So what I want is the following: fill the list with random numbers, but when I re-execute the script, I want the same "random" numbers in the same order. This way each sorting alg. would get the same input. As a workaround, I made a generator that outputs a random list in a file, and this list is read each time by the testing script. I just wonder if there is a more elegant solution. Thanks, Laszlo -- http://mail.python.org/mailman/listinfo/python-list
Re: generate random numbers in a deterministic way
Assuming you're using the Python's random module, which works based on the Mersenne Twister, you can preset the seed with random.seed(hashable). More details here: http://docs.python.org/library/random.html#random.seed ~Temia On Wed, 25 Apr 2012 07:51:18 +0200, you wrote: >Hi, > >I'm working with some sorting algorithms and I want to compare their >efficiency. One test fills a list with one million random integers, >which serves as input for the algorithms. However, if this list is >different each time I run the tests, the tests wouldn't be fair. At >the moment the selected sorting alg. can be specified with a switch >and only one alg. is tested each time. > >So what I want is the following: fill the list with random numbers, >but when I re-execute the script, I want the same "random" numbers in >the same order. This way each sorting alg. would get the same input. > >As a workaround, I made a generator that outputs a random list in a >file, and this list is read each time by the testing script. I just >wonder if there is a more elegant solution. > >Thanks, > >Laszlo -- When on earth, do as the earthlings do. -- http://mail.python.org/mailman/listinfo/python-list
Download now
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Same code cause the different result.
Hi, all I have code as: /pobj = subprocess.Popen (["smbpasswd", user], stdin =subprocess.PIPE) password += "\n" pobj.stdin.write (password) pobj.stdin.write (password)/ the command smbpasswd will change the samba user's password, In shell this will run as below: /[root@localhost ~]# smbpasswd mytest1 New SMB password: Retype new SMB password: [root@localhost ~]# / but in python code, it always prompt to wait input the password, it is seems that pobj.stdin.write () doesn't work. It is anything wrong with my code? I have another block code that runs as expected: /pobj = subprocess.Popen (["passwd", user], stdin = subprocess.PIPE) password = password + "\n" pobj.stdin.write (password) pobj.stdin.write (password)/ It is so curious and I wonder why.It is the same result when substitute smbpasswd with pdbedit. -- http://mail.python.org/mailman/listinfo/python-list
