Mailman 3 April 2007 - Python-Dev

Re: [Python-Dev] [Python-3000] Pre-pre PEP for 'super' keyword
by Jim Jewett 04 May '07

04 May '07

On 4/29/07, Tim Delaney <tcdelaney(a)optusnet.com.au> wrote: > I've been intending to write up a PEP for fixing super, but I haven't had > time to get to it. Calvin Spealman has the most recent draft. I hope he will incorporate this into his draft. > 1. 'super' becomes a keyword, that returns a super object for the instance > method currently being executed. So it is a "keyword" in the sense that None is a keyword; not in the stronger sense that "if" is a keyword? > 4. super objects are callable, and calling them will execute the super > method with the same name as the instance method currently being executed. > Lookup of this method occurs when the instance method is entered. > > class A(object): > def f(self): > pass > > class B(A): > def f(self): > super() # Calls A.f(self) > If you want name lookup to occur at the time of the call, you can explicitly > specify the method name (just like with any other super attribute): > > class A(object): > def f(self): > pass > > class B(A): > def f(self): > super.f() # Calls A.f(self) As long as you can be explicit, should the shortcut be a full shortcut? That is, def f(self, a, b=c, *args, **kwargs): super() # passes the exact arglist that f got vs def __init__(self, myvar, passed_var): super.__init__(self, passed_var) # flags that you are changing the args -jJ

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New operations in Decimal
by Facundo Batista 01 May '07

01 May '07

The following are the new operations in the decimal module that we'll be available according to the last published specification. I wrote here the proposed name by me, the original name between parenthesis, where it will be located between square brackets (C for context and D for the decimal object itself), and a small description of the operation (I specially trimmed the verbose special cases from the description, if you want an exact explanation of what does each, read the spec). Note that always it says how many operands it takes. The number implies you're calling it through the context. If called through Decimal, you have to substract one from it (as the first operand will be the number itself in this case). Enjoy it, and any feedback is very appreciated, :) - compare_signal (compare–signal) [CD]: Takes two operands and compares their values numerically (pretty much like compare(), but all NaNs signal, with signaling NaNs taking precedence over quiet NaNs. - fma (fused-multiply-add) [C]: Takes three operands; the first two are multiplied together, using multiply, the third operand is then added to the result of that multiplication, using add, all with only one final rounding. - ln (ln) [CD]: Takes one operand, and the result is the natural (base e) logarithm of the operand. - log10 (log10) [CD]: Takes one operand, and the result is the base 10 logarithm of the operand. - max_mag (max–magnitude), and min_mag (min-magnitude) [CD]: Takes two operands and compares their values numerically with their sign ignored. - next_minus (next–minus) [CD]: Takes one operand and the result is the largest representable number that is smaller than the operand. - next_plus (next–plus) [CD]: Takes one operand and the result is the smallest representable number that is larger than the operand. - next_toward (next–toward) [CD]: Takes two operands and the result is the representable number closest to the first operand (but not the first operand) that is in the direction towards the second operand, unless the operands have the same value. - to_integral_exact (round-to-integral-exact) [C]: Takes one operand. It is similar to the round–to–integral–value (the old to_integral), with the difference the now Inexact and Rounded flags are allowed in the result. The following operations appear in a new section of the specification called "Miscelaneous Operations". Between these are logical operations that take logical operands, which are finite positive non-exponent numbers with a coefficient whose digits must all be either 0 or 1. - and (and), or (or), xor (xor) [CD]: Takes two logical operands, the result is the logical operation applied between each digit. - canonical (canonical) [CD]: Canonical takes one operand, returns the same Decimal object, as we do not have different encodings for the same number. - number_class (class) [CD]: Takes one operando, returns an indication of the class of the operand, where the class is one of the following: "sNaN", "NaN", "–Infinity", "–Normal", "–Subnormal", "–Zero", "+Zero", "+Subnormal", "+Normal" or "+Infinity". - compare_total (compare–total) [CD]: Takes two operands and compares them using their abstract representation rather than their numerical value (a total ordering is defined for all possible abstract representations). - compare_total_mag (compare–total–magnitude) [CD]: Takes two operands and compares them using their abstract representation rather than their numerical value, with their sign ignored and assumed to be 0. - copy_abs (copy-abs) [CD]: Takes one operand, returns a copy of it with the sign set to 0. - copy_negate (copy-negate) [CD]: Takes one operand, returns a copy of it with the sign inverted. - copy_sign (copy–sign) [CD]: Takes two operands, returns a copy of the first operand with the sign equal to the sign of the second operand. - invert (invert) [CD]: Takes one logical operand, the result is the digit-wise inversion of the operand. - is-canonical (is–canonical) [CD]: Takes one operand, returns 1 if the operand is canonical; otherwise returns 0. - is_finite (is–finite) [CD]: Takes one operand, returns 1 if the operand is neither infinite nor a NaN, otherwise returns 0. - is_infinite (is–infinite) [CD]: Takes one operand, returns 1 if the operand is an Infinite, otherwise returns 0. - is_nan (is–NaN) [CD]: Takes one operand, returns 1 if the operand is a quiet or signaling NaN, otherwise returns 0. - is_normal (is–normal) [CD]: Takes one operand, returns 1 if the operand is a positive or negative normal number, otherwise returns 0. - is_qnan (is–qNaN) [CD]: Takes one operand, returns 1 if the operand is a quiet NaN, otherwise returns 0. - is_signed (is–signed) [CD]: Takes one operand, returns 1 if the sign of the operand is 1, otherwise returns 0. - is_snan (is–sNaN) [CD]: Takes one operand, returns 1 if the operand is a signaling NaN, otherwise returns 0. - is_subnormal (is–subnormal) [CD]: Takes one operand, returns 1 if the operand is a positive or negative subnormal number, otherwise returns 0. - is_zero (is–zero) [CD]: Takes one operand, returns 1 if the operand is a zero, otherwise returns 0. - logb (logb) [CD]: Takes one operand, returns the integer which is the exponent of the magnitude of the most significant digit of the operand (as though the operand were truncated to a single digit while maintaining the value of that digit and without limiting the resulting exponent). - radix (radix) [CD]: Takes no operands, returns 10. - rotate (rotate) [CD]: Takes two operands. The coefficient of the result is a rotated copy of the digits in the coefficient of the first operand. The number of places of rotation is taken from the absolute value of the second operand, with the rotation being to the left if the second operand is positive or to the right otherwise. - scaleb (scaleb) [CD]: Takes two operands. The result is the first operand modified by adding the value of the second operand to its exponent. - shift (shift) [CD]: Takes two operands. The coefficient of the result is a shifted copy of the digits in the coefficient of the first operand. The number of places to shift is taken from the absolute value of the second operand, with the shift being to the left if the second operand is positive or to the right otherwise. Digits shifted into the coefficient are zeros. Regards, -- . Facundo . Blog: http://www.taniquetil.com.ar/plog/ PyAr: http://www.python.org/ar/

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Python 2.5.1
by Khalid A. Bakr 01 May '07

01 May '07

Hello I downloaded Python's 2.5.1 (final) bz2 source archive the other day to try to compile it in MinGW. I have noted down the following observations that might be of interest. 1. The bz2 archive ships with \Modules\collectionsmodule.c instead of the \Modules\_collectionsmodule.c used in the 2.5 SVN branch. In fact the collectionsmodule.c was removed some time ago. 2. If _collectionsmodule.c is the one to be used in branch and source then it follows that \PC\config.c needs an update. 3. test_1686475 of test_os appears to rely on the existence of "c:\pagefile.sys" like so: def test_1686475(self): # Verify that an open file can be stat'ed try: os.stat(r"c:\pagefile.sys") except WindowsError, e: if e == 2: # file does not exist; cannot run test return self.fail("Could not stat pagefile.sys") But since that file does not appear to be in my C drive and since the Windows error returned is not a numeric, but rather a string of the sort: "[Error 5] Access is denied: 'c:\\pagefile.sys'" then that test fails for me both in the MinGW compiled Python and in the officially distributed one. 4. Also test_1565150 of test_os which reads as follows: # Restrict test to Win32, since there is no guarantee other # systems support centiseconds if sys.platform == 'win32': def test_1565150(self): t1 = 1159195039.25 os.utime(self.fname, (t1, t1)) self.assertEquals(os.stat(self.fname).st_mtime, t1) fails in the MinGW compiled Python with the following message: ====================================================================== FAIL: test_1565150 (test.test_os.StatAttributeTests) ---------------------------------------------------------------------- Traceback (most recent call last): File "G:\projs\py25\python\r25\lib\test\test_os.py", line 241, in test_1565150 self.assertEquals(os.stat(self.fname).st_mtime, t1) AssertionError: 1159195040 != 1159195039.25 If the same test passes in the official CPython on the same machine (and it does), can it then be deduced that this is not a system's issue but a compiler one? Thanks Khalid __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

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os.rename on windows
by Raghuram Devarakonda 01 May '07

01 May '07

Hi, I have submitted a patch (http://www.python.org/sf/1704547) that allows os.rename to replace the destination file if it exists, on windows. As part of discussion in the tracker, Martin suggested that python-dev should discuss the change. Currently, os.rename() on windows uses the API MoveFile() which fails if the destination file exists. The patch replaces this API with MoveFileEx() and uses the flag MOVEFILE_REPLACE_EXISTING which causes the destination file to be replaced if it exists. However, this change is subtle and if there is any existing code that depends on current os.rename behaviour on windows, their code is silently broken with (any) destination file being overwritten. But the functionality of replacing is important and I would like to know the best of way of supporting it. If it is deemed that this change is not good to go in as-is, how about having an optional parameter to os.rename (say, win_replace) that can be used by callers to explicitly request replacing? I must also point out that the patch uses another flag MOVEFILE_COPY_ALLOWED effectively allowing renamed files to be on separate file systems. The renaming in this case is not atomic and I used this flag only to support current functionality. It is not a bad idea to disallow such renames which brings it in line with the behaviour on many unix flavors. This also has the potential to break code but not silently. Lastly, I found an old discussion about the same topic by this list. http://mail.python.org/pipermail/python-dev/2001-May/014957.html Even though Guido indicated that he doesn't support API change in this thread, I am posting again as I did not see any one mention MoveFileEx() in that thread. Thanks, Raghu.

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(no subject)
by JOSHUA ABRAHAM 01 May '07

01 May '07

I was hoping you guys would consider creating function in os.path or otherwise that would find the full path of a file when given only it's base name and nothing else.I have been made to understand that this is not currently possible.If it is in any can you please inform me of it[i know this is not a tutorial] but please i need thiis badly if it's possible.Thank you _________________________________________________________________ FREE pop-up blocking with the new MSN Toolbar - get it now! http://toolbar.msn.click-url.com/go/onm00200415ave/direct/01/

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Call for junior PEP editors
by Barry Warsaw 01 May '07

01 May '07

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 David Goodger and I have been the PEP editors for ages. Well, mostly David lately as I've been way too busy to be of much use. David is also pretty busy, and he lamented that he doesn't have much time for editing when he put out his call for PEPs earlier this month. We've now, or will soon have three more experienced Pythonistas helping out as PEP editors, Georg Brandl, Brett Cannon, and Anthony Baxter. As long as they've been hacking Python, you'd have thought they'd have learned their lesson by now, but we'll gladly consume more of their time and souls. David and I would like to see some junior Pythonistas join the PEP editor team, as a great way to gain experience and become more involved with the community. As David says, PEP editing is something a tech writer can do; it doesn't require intimate knowledge of Python's C code base for example. PEP editors don't judge the worthiness of a PEP -- that's for the Python community to do, but they do the important work of ensuring that the PEPs are up to the high quality and consistent standards that have been established over the years. A PEP editor is sometimes also involved in the meta process of developing and maintaining the PEPs. A good editor's eye, excellent written communication skills, and the inhuman amount of spare time that only the young have are your most important qualifications. If you're a budding Pythonista and are interested in becoming a PEP editor, please send an email to peps(a)python.org. Let us know about your writing and/or editing experience, how long you've been using Python, how long you've been programming in general, and how much cash you'll be sending our way. Kidding about that last bit. python- dev lurkers are encouraged to apply! Again, this call is for junior Pythonistas only. I think we have enough experienced people now to cover our bases and to help mentor new editors. We're really eager to get some new blood involved in the Python community. We may not accept all applicants; we're aiming for two or three additional editors, but that number isn't set in stone. Cheers, - -Barry (and David) -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.5 (Darwin) iQCVAwUBRjZzeXEjvBPtnXfVAQIzFAQAhj1VIaa+QZ6+7O2BlmDGgCzXiJt1Yfb+ uz8HxVfL+5wjXeQELAPM0hxp07qKtq8ys131gZI19BtGe8F+imzEIkyZJvHrJYNw vOboLs9cSJuDlH0QCKT5p9HNf9H75tm5gOFiCTnDDKJ4/BRzsUG62EHDd4Tz9brq euEKecOMiwk= =vNz1 -----END PGP SIGNATURE-----

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deprecating macpath and macurl2path
by Neal Norwitz 30 Apr '07

30 Apr '07

PEP 11 notes that Mac OS 9 support was unsupported in 2.4. There are still quite a few places that we check for sys.platform == 'mac'. There are also (at least) 2 modules (macpath and macurl2path) that look specific to Mac OS. (OS X has sys.platform == 'darwin'.) Shall I add a deprecation warning on import to these modules or remove them? I plan to remove other mac specific code (checking sys.platform) in the stdlib unless someone beat me to it. n

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Re: [Python-Dev] New Super PEP
by Armin Rigo 30 Apr '07

30 Apr '07

Hi Calvin, On Mon, Apr 30, 2007 at 08:34:56AM -0400, Calvin Spealman wrote: > If you want, you can also grab the reference > implementation from my blog: http://ironfroggy-code.blogspot.com/ This reference implementation is broken. It doesn't pass the following test, for example: class A(object): __metaclass__ = autosuper def f(self): if type(self) is B: return "we've got a B" else: return "oups" class B(A): def f(self): return Super.f() assert B().f() == "we've got a B" I don't honestly think that you can easily fix the implementation to pass this test, but I'm ready to check proposed fixes and write tests for them. If there is really no working implementation yet then it shouldn't have been a PEP posted on python-dev in the first place, IMHO (and the discussion shouldn't go on on python-dev either). A bientot, Armin.

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test_pty fails on Sparc Solaris 10 for trunk
by Grig Gheorghiu 30 Apr '07

30 Apr '07

This is happening both in the Python buildbot farm, and in the community buildbot farm. See: http://www.python.org/dev/buildbot/trunk/sparc%20solaris10%20gcc%20trunk/bu… http://www.python.org/dev/buildbot/community/trunk/sparc%20Solaris%2010%20t… Grig -- http://agiletesting.blogspot.com

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Re: [Python-Dev] [Python-3000] Pre-pre PEP for 'super' keyword
by Delaney, Timothy (Tim) 30 Apr '07

30 Apr '07

Jim Jewett wrote: > On 4/29/07, Tim Delaney <tcdelaney(a)optusnet.com.au> wrote: >> I've been intending to write up a PEP for fixing super, but I >> haven't had time to get to it. > > Calvin Spealman has the most recent draft. I hope he will incorporate > this into his draft. Sorry about this - wasn't receiving python-dev at home, so didn't realise Calvin had released the PEP. I think the current PEP draft is way too complicated - I don't think there's any need for descriptors, etc. I think we can make things work in the following way: 1. When a method is defined, the class is bound to it via an attribute (which in my version is called func_class). 2. Every non-static method has an implicit cell variable called 'super'. This would preferably not be able to be rebound. I also think it would be beneficial if the first parameter to the method couldn't be rebound (point 7 in my original email in this thread). 3. When a method is entered, the 'super' cell variable is populated by a call equivalent to: super = __builtin__.super(func_class, first_parameter) This would result in 'super' being a constant object, within the scope of the currently-executing method. 'keyword' was perhaps too strong - I was thinking this would only need to be done if 'super' were actually used, which would be easier to determine if 'super' actually were a keyword. This could still be done by not emitting the above call unless the 'super' cell variable were ever actually used. I've done bytecode-hacky stuff to do the equivalent of the above (as much as I've been able to), but a real implementation would just emit the correct bytecode (or java bytecode, or whatever) in the compiled code object. The issue of super() vs. super.__call__() ambiguity - I'll need to look at that when I get home. I'm a strong -1 against super() automatically passing the parameters that were passed to the currently-executing method. Tim Delaney

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