Bugs item #1165306, was opened at 2005-03-17 15:56 Message generated for change (Comment added) made by remyblank You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1165306&group_id=5470
Category: Python Interpreter Core Group: Python 2.3 Status: Open Resolution: None Priority: 6 Submitted By: Remy Blank (remyblank) Assigned to: Michael Hudson (mwh) Summary: Property access with decorator makes interpreter crash Initial Comment: The attached file makes the interpreter crash. Basially, a method is decorated, and used as the getter function for a property. Accessing the property provokes the crash. I get the following output (linux-2.6.10): [EMAIL PROTECTED] TestCases $ ./crashTest.py Creating instance Getting value Segmentation fault Using python-2.3.4 from Gentoo, i.e. it has a few patches from 2.3.5. On Windows XP with python-2.4, I get a "Python has encountered a problem and needs to close." dialog box. ---------------------------------------------------------------------- >Comment By: Remy Blank (remyblank) Date: 2005-03-17 21:13 Message: Logged In: YES user_id=568100 > remyblank: let me guess your code wasn't doing what you thought it did? :) Err... Not sure what you mean... What would be the correct way to do what I thought it did? The code was largely inspired by a Cookbook entry. These are still my first steps with decorators, and I have to admit I don't yet fully understand why I have to create a MethodType manually. ---------------------------------------------------------------------- Comment By: Guido van Rossum (gvanrossum) Date: 2005-03-17 19:43 Message: Logged In: YES user_id=6380 Looks OK on cursory inspection. ---------------------------------------------------------------------- Comment By: Michael Hudson (mwh) Date: 2005-03-17 18:28 Message: Logged In: YES user_id=6656 Let's attach a test case too. ---------------------------------------------------------------------- Comment By: Michael Hudson (mwh) Date: 2005-03-17 18:15 Message: Logged In: YES user_id=6656 Well, it's a bit more subtle than I thought: >>> def f(): pass ... >>> print f.__get__(1).im_class None The problem occurs when *both* im_self and im_class are None; and I'm now reasonably convinced that calling the type object is the only way this can be acheived. So a simple check along these lines in instancemethod_new would suffice (patch attached), and seems less likely to break code. I suspect this has missed 2.4.1. remyblank: let me guess your code wasn't doing what you thought it did? :) ---------------------------------------------------------------------- Comment By: Guido van Rossum (gvanrossum) Date: 2005-03-17 18:03 Message: Logged In: YES user_id=6380 Looks like I wasn't finished with the thought when I checked it in. I think I was trying to make instancemethod generally useful as a currying primitive. That should probably be considered more careful; please roll it back. (I think it may have been part of the aborted experiment to get rid of bound methods.) Is there time to backport this to 2.4.1? ---------------------------------------------------------------------- Comment By: Michael Hudson (mwh) Date: 2005-03-17 17:44 Message: Logged In: YES user_id=6656 Hmm. A little CVS log reading finds us this: revision 2.170 date: 2003/04/09 19:35:08; author: gvanrossum; state: Exp; lines: +2 -2 branches: 2.170.10; Make it possible to call instancemethod() with 2 arguments. Guido, what was the motivation for this? Is it possible to create instancemethods with im_class == NULL some other way? (If there is, I don't see it). Also, you didn't add a unit test <poke> (in fact, instancemethod_new only gets called twice during a run of the test suite, both times with three arguments). ---------------------------------------------------------------------- Comment By: Michael Hudson (mwh) Date: 2005-03-17 16:17 Message: Logged In: YES user_id=6656 Confirmed, on 2.4 HEAD, even. There's a lot going on in your test file that is unecessary, though; this is a smaller test case: types.MethodType(lambda :None, None)(1) instancemethod_call doesn't seem to expect im_class to be NULL... ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1165306&group_id=5470 _______________________________________________ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
