Mailman 3 April 2001 - Python-Dev

SF changing directory structure
by Martin v. Loewis 27 Apr '01

27 Apr '01

As some of you may have noticed, the Python web pages are now in /home/groups/p/py/python on SourceForge; the symbolic link /home/groups/python will be removed shortly. There might be still a number of files that refer to the old location, atleast htdocs/sf-faq.html, and perhaps crontabs. Whoever is in charge of these should probably update them. Regards, Martin

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Memory management question
by Thomas Heller 27 Apr '01

27 Apr '01

I'm trying to port Don Beaudry's objectmodule to Python 2.0 and encountered the following problem. Here is a part from Don's code: co = (MetaClassObject*) PyClass_New(NULL, methods, name); co = PyObject_Realloc(co, sizeof (MetaClassObject)); As you see, he is trying to achive cheap code reuse. This code does not work. I have tracked it down to the following sample, which does also not work. In the debug version on windows, the PyObject_REALLOC fails with an assertion-error: _CrtIsValidHeapPointer(pUserData) op = PyObject_NEW(PyClassObject, &PyClass_Type); op = PyObject_REALLOC(op, sizeof(PyClassObject) + 20); Should the above work or am I doing something wrong? Regards, Thomas

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Re: [ python-Bugs-416670 ] MatchObjects not deepcopy()able
by Fredrik Lundh 27 Apr '01

27 Apr '01

> In the re-Module which come with Python version 2.0 > (Nov 28 11:10 re.py) the created MatchObjects cannot be > copied with a deepcopy(). Switching back to the old > "pre.py" as proposed in "re.py" makes everything work > ok. thought I'd check this one with python-dev before marking it as "won't fix". I cannot see any reason why anyone would even attempt to deepcopy match objects... (cannot see any reason why anyone would use deepcopy for anything, but that's another story) Cheers /F

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FW: how will you be writing code 10 years from now?
by Greg Wilson 27 Apr '01

27 Apr '01

The following is a webcast from a (preliminary non-official) meeting on C++0x (C++, the next generation). Could be a bit of foreshadowing on how things will develop (or prove to be giant red herring if they decide not to follow any of these ideas) http://technetcast.ddj.com/tnc_play_stream.html?stream_id=560

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[ python-Bugs-416670 ] MatchObjects not deepcopy()able
by Martin v. Loewis 26 Apr '01

26 Apr '01

> thought I'd check this one with python-dev before marking it as > "won't fix". I cannot see any reason why anyone would even attempt > to deepcopy match objects... What's wrong with patch #419070, which fixes the bug? Like any other immutable object, deepcopying a match object means returning it. Regards, Martin

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Re: [Python-Dev] anyone have an Irix box?
by Michael Hudson 26 Apr '01

26 Apr '01

"Fredrik Lundh" <fredrik(a)effbot.org> writes: > SRE doesn't work at all under Irix8/gcc, according to this report > https://sourceforge.net/tracker/?func=detail&aid=233790&group_id=5470&atid=… > > unfortunately, the submitter didn't provide any contact info, and > hasn't bothered to follow up with more details. and I still don't > have a working SGI box. > > any ideas how to deal with this? Quinn Dunkan (quinn at dinar.ugcs.caltech.edu) has/had an Irix box he could test stuff on (I tried to help him sort some readline stuff out once but got nowhere). I'm sure he would run make test and email you the output if you asked nicely. While not ideal, if it works for him it would give you more justification in closing the report unless the OP comes up with some more info. Cheers, M. -- Just put the user directories on a 486 with deadrat7.1 and turn the Octane into the afforementioned beer fridge and keep it in your office. The lusers won't notice the difference, except that you're more cheery during office hours. -- Pim van Riezen, asr

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anyone have an Irix box?
by Fredrik Lundh 26 Apr '01

26 Apr '01

SRE doesn't work at all under Irix8/gcc, according to this report https://sourceforge.net/tracker/?func=detail&aid=233790&group_id=5470&atid=… unfortunately, the submitter didn't provide any contact info, and hasn't bothered to follow up with more details. and I still don't have a working SGI box. any ideas how to deal with this? Cheers /F

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buffer interface (again)
by Thomas Heller 26 Apr '01

26 Apr '01

I would like to use (again) the buffer interface, and I have some suggestions/questions. - Only extension types can implement the buffer interface, no way for a python class. Maybe a magic method __buffer__(self) could be invented for this purpose? - Why does the builtin function buffer() always return readonly buffers, even for read/write objects? Shouldn't there also be a readwrite_buffer() function, or should buffer() return read/write buffers for read/write objects? - My bug report 216405 on sourceforge is still open (well, it is marked as closed, but it went into PEP 42) http://sourceforge.net/tracker/index.php?func=detail&aid=216405&group_id=54… Regards, Thomas

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ANN: mxNumber -- Experimental Number Types, Version 0.2.0
by M.-A. Lemburg 25 Apr '01

25 Apr '01

ANNOUNCING mxNumber - Version 0.2.0 Python Interface to GNU MP Number Types INTRODUCTION ------------ As you all know, Moshe Zadka has been pushing for a new rational number type recently (at the conference) and also implemented a proof- of-concept implementation of his rational PEP 239. Since the GNU Multi-Precision Lib (GMP) already has all these tools providing what people want most when it comes to numbers (precision and speed), I thought that wrapping these as Python types would be a good idea. I know that Alex Martelli has been working on a similar approach, but that project (gmpy) seems to be inactive. Anyway, even though the GMP is available for most Unix platforms and MacOS, there was no relyable port for Windows. This was a show- stopper for me, so I decided to port GMP to Windows, which was harder than I thought, but well, it's done now. There's still no web-page for this package, so I'm providing the needed information in this posting. WHAT'S NEW ? ------------ The 0.2.0 release is an alpha release. Everything is still in flux, so expect bugs, strange behaviour etc. Still, the package provides some interesting insights into the issues you run into when dealing with computational representations of numbers. For now, you should consider the package a pure fun-package and playground for experiments. New in this release are a parser for rational strings (formats "1/2" and "3 1/3"), plus a new constructor FareyRational() which was inspired by an algorithm written by Scott David Daniels and posted to the Python Cookbook; see http://www.activestate.com/ASPN/Python/Cookbook/Recipe/52317 The FareyRational() constructor allows you to convert floating point numbers to rationals, e.g. 1.3333 to 4/3. INTERFACE --------- The package is part of the eGenix.com EXPERIMENTAL package and called mx.Number. It provides access to three numerical types: 1. Integer(value) -- arbitrary precision integers much like Python long only faster 2. Rational(nom,denom) -- rational numbers with Integers as numerator and denominator 3. Float(value[,prec]) -- floating point number with at least prec bits precision 4. FareyRational(value, maxden) -- calculate the best rational represenation n/d of value such that d < maxden DOWNLOADS --------- * GMP 3.1.1 - Unix: GMP 3.1.1 must be installed (http://www.swox.com/gmp/) - Windows: GMP 3.1.1 is included in the download archives for Windows * Python 2.1 * Optional: egenix-mx-base package available from http://www.lemburg.com/files/python/ * The "egenix-mx-experimental" package which includes mx.Number: Source: http://www.lemburg.com/files/python/egenix-mx-experimental-0.2.0.zip RPM: http://www.lemburg.com/files/python/egenix-mx-experimental-0.2.0-1.i386-py2… Windows installer: http://www.lemburg.com/files/python/egenix-mx-experimental-0.2.0.win32-py2.… Usage is simple: ---------------- from mx.Number import * f = Float(3.141) r1 = Rational(3.141) r2 = Rational(2, 3) r3 = FareyRational(1.33333, 1000) i = Integer("1231231231231231231231231") The coercion model will (someday) look like this: Float ^ | --------> Python float | ^ | | | Rational | ^ | | Python long -----> Integer ^ ^ | | -------- Python integer Complex numbers are not integrated into the picture since I think that they should not be auto-coerced. Some of these arrows are not implemented yet, others are not shown (e.g. Integer(2) + "3" works as one would expect ;-). Note that this is still a very rough version. Feedback is welcome. QUESTIONS --------- * What do you think about this coercion model ? Shouldn't we have a PEP for this ? * Please try out the rational type and see if it fits your needs -- the results are sometimes surprising (due to the IEEE representations of floats); I'm sure this proof of concept will raise a few more questions regarding the usefulness of switching to rationals for literals like 1.123. * This implementation also showed that even though the coercion patches have made integraton of numerical types easier, a full integration is still hard to achieve. Some issues: - string formatting cannot be "overridden" to allow formatting of these new types - there is no way of providing PyArg_ParseTuple() parser markers for the types - there is no way to bind the types to a Python literal, e.g. by specifying a number literal modifier which is then bound to the type: 1234L -> long("1234"), 1234.123F -> Float("1234.123"), 2R / 3 -> Rational(2, 3) etc. Comments ? -- Marc-Andre Lemburg ______________________________________________________________________ Company & Consulting: http://www.egenix.com/ Python Software: http://www.lemburg.com/python/

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ANN: mxNumber -- Experimental Number Types, Version 0.2.0
by M.-A. Lemburg 25 Apr '01

25 Apr '01

ANNOUNCING mxNumber - Version 0.2.0 Python Interface to GNU MP Number Types INTRODUCTION ------------ As you all know, Moshe Zadka has been pushing for a new rational number type recently (at the conference) and also implemented a proof- of-concept implementation of his rational PEP 239. Since the GNU Multi-Precision Lib (GMP) already has all these tools providing what people want most when it comes to numbers (precision and speed), I thought that wrapping these as Python types would be a good idea. I know that Alex Martelli has been working on a similar approach, but that project (gmpy) seems to be inactive. Anyway, even though the GMP is available for most Unix platforms and MacOS, there was no relyable port for Windows. This was a show- stopper for me, so I decided to port GMP to Windows, which was harder than I thought, but well, it's done now. There's still no web-page for this package, so I'm providing the needed information in this posting. WHAT'S NEW ? ------------ The 0.2.0 release is an alpha release. Everything is still in flux, so expect bugs, strange behaviour etc. Still, the package provides some interesting insights into the issues you run into when dealing with computational representations of numbers. For now, you should consider the package a pure fun-package and playground for experiments. New in this release are a parser for rational strings (formats "1/2" and "3 1/3"), plus a new constructor FareyRational() which was inspired by an algorithm written by Scott David Daniels and posted to the Python Cookbook; see http://www.activestate.com/ASPN/Python/Cookbook/Recipe/52317 The FareyRational() constructor allows you to convert floating point numbers to rationals, e.g. 1.3333 to 4/3. INTERFACE --------- The package is part of the eGenix.com EXPERIMENTAL package and called mx.Number. It provides access to three numerical types: 1. Integer(value) -- arbitrary precision integers much like Python long only faster 2. Rational(nom,denom) -- rational numbers with Integers as numerator and denominator 3. Float(value[,prec]) -- floating point number with at least prec bits precision 4. FareyRational(value, maxden) -- calculate the best rational represenation n/d of value such that d < maxden DOWNLOADS --------- * GMP 3.1.1 - Unix: GMP 3.1.1 must be installed (http://www.swox.com/gmp/) - Windows: GMP 3.1.1 is included in the download archives for Windows * Python 2.1 * Optional: egenix-mx-base package available from http://www.lemburg.com/files/python/ * The "egenix-mx-experimental" package which includes mx.Number: Source: http://www.lemburg.com/files/python/egenix-mx-experimental-0.2.0.zip RPM: http://www.lemburg.com/files/python/egenix-mx-experimental-0.2.0-1.i386-py2… Windows installer: http://www.lemburg.com/files/python/egenix-mx-experimental-0.2.0.win32-py2.… Usage is simple: ---------------- from mx.Number import * f = Float(3.141) r1 = Rational(3.141) r2 = Rational(2, 3) r3 = FareyRational(1.33333, 1000) i = Integer("1231231231231231231231231") The coercion model will (someday) look like this: Float ^ | --------> Python float | ^ | | | Rational | ^ | | Python long -----> Integer ^ ^ | | -------- Python integer Complex numbers are not integrated into the picture since I think that they should not be auto-coerced. Some of these arrows are not implemented yet, others are not shown (e.g. Integer(2) + "3" works as one would expect ;-). Note that this is still a very rough version. Feedback is welcome. QUESTIONS --------- * What do you think about this coercion model ? Shouldn't we have a PEP for this ? * Please try out the rational type and see if it fits your needs -- the results are sometimes surprising (due to the IEEE representations of floats); I'm sure this proof of concept will raise a few more questions regarding the usefulness of switching to rationals for literals like 1.123. * This implementation also showed that even though the coercion patches have made integraton of numerical types easier, a full integration is still hard to achieve. Some issues: - string formatting cannot be "overridden" to allow formatting of these new types - there is no way of providing PyArg_ParseTuple() parser markers for the types - there is no way to bind the types to a Python literal, e.g. by specifying a number literal modifier which is then bound to the type: 1234L -> long("1234"), 1234.123F -> Float("1234.123"), 2R / 3 -> Rational(2, 3) etc. Comments ? -- Marc-Andre Lemburg ______________________________________________________________________ Company & Consulting: http://www.egenix.com/ Python Software: http://www.lemburg.com/python/

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