[issue8300] Allow struct.pack to handle objects with an __index__ method.
Matt Joiner anacro...@gmail.com added the comment: Why isn't this implemented to work with __int__ as well? -- nosy: +anacrolix ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue8300 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue8300] Allow struct.pack to handle objects with an __index__ method.
Mark Dickinson dicki...@gmail.com added the comment:
Because (arguably) we don't want to be able to pack non-integral floats (or
Decimal instances, or ...) using integer formats:
import struct
[56090 refs]
struct.pack('L', 2.3)
Traceback (most recent call last):
File stdin, line 1, in module
struct.error: required argument is not an integer
[56125 refs]
--
___
Python tracker rep...@bugs.python.org
http://bugs.python.org/issue8300
___
___
Python-bugs-list mailing list
Unsubscribe:
http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue8300] Allow struct.pack to handle objects with an __index__ method.
Matt Joiner anacro...@gmail.com added the comment: Thanks Mark for clearing that up. I found this link to be useful in explaining the purpose of __index__: http://docs.python.org/release/2.5.1/whatsnew/pep-357.html I think the choice of allowing only __index__ was the right choice. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue8300 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue8300] Allow struct.pack to handle objects with an __index__ method.
Mark Dickinson dicki...@gmail.com added the comment: Thanks. -- status: open - closed ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue8300 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue8300] Allow struct.pack to handle objects with an __index__ method.
Mark Dickinson dicki...@gmail.com added the comment: Probably both those conditions can't be satisfied; I'm wasn't sure what happened if something's __index__ method returned something other than an int or long. But now I bother to look at the source (in Objects/abstract.c) I see that there *is* already an explicit check for the result of nb_index being int or long (with TypeError being raised if the result isn't one of those). Mea culpa. I'll remove those lines (though I may leave an assert, just to be on the safe side). The 2.x behaviour isn't ideal: I'd prefer to just stop if the __index__ method is present and raises TypeError, rather than going on to check __int__ in that case. But that presents problems with old-style classes, where PyIndex_Check is true even when no __index__ method is explicitly defined. Thanks for the extra tests! -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue8300 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue8300] Allow struct.pack to handle objects with an __index__ method.
Mark Dickinson dicki...@gmail.com added the comment: Committed (with some tabs in test_struct.py changed to spaces) to trunk in r79745. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue8300 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue8300] Allow struct.pack to handle objects with an __index__ method.
Mark Dickinson dicki...@gmail.com added the comment: Merged to py3k in r79746. Meador, does this all look okay, now? -- resolution: - accepted stage: patch review - committed/rejected status: open - pending ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue8300 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue8300] Allow struct.pack to handle objects with an __index__ method.
Meador Inge mead...@gmail.com added the comment: Looks good to me. -- status: pending - open ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue8300 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue8300] Allow struct.pack to handle objects with an __index__ method.
New submission from Mark Dickinson dicki...@gmail.com:
In Python 2.7, struct.pack with an integer format can handle non-integers that
provide an __int__ method (although this *does* raise a DeprecationWarning).
Python 2.7a4+ (trunk:79659:79661, Apr 3 2010, 11:28:19)
[GCC 4.2.1 (Apple Inc. build 5646) (dot 1)] on darwin
Type help, copyright, credits or license for more information.
from struct import pack
[35194 refs]
pack('L', 3.1415)
'\x03\x00\x00\x00\x00\x00\x00\x00'
[35210 refs]
This behaviour isn't particularly desirable for floats or Decimal instances,
but it's useful for integer-like objects.
In Python 3.x, there's no provision for handling integer-like objects than
aren't actually integers.
I propose that in 3.x, struct.pack should try to convert any non-integer to an
integer by using its __index__ method, before packing.
--
assignee: mark.dickinson
messages: 102245
nosy: mark.dickinson
severity: normal
status: open
title: Allow struct.pack to handle objects with an __index__ method.
versions: Python 3.2
___
Python tracker rep...@bugs.python.org
http://bugs.python.org/issue8300
___
___
Python-bugs-list mailing list
Unsubscribe:
http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue8300] Allow struct.pack to handle objects with an __index__ method.
Changes by Mark Dickinson dicki...@gmail.com: -- components: +Extension Modules stage: - test needed type: - feature request ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue8300 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue8300] Allow struct.pack to handle objects with an __index__ method.
Mark Dickinson dicki...@gmail.com added the comment: Here's a patch for trunk. It combines the docs and tests from Meador Inge's patch in issue 1530559 with a C-level change to get_pylong in Modules/struct.c. -- keywords: +patch versions: +Python 2.7 Added file: http://bugs.python.org/file16746/struct_index_trunk.patch ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue8300 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue8300] Allow struct.pack to handle objects with an __index__ method.
Mark Dickinson dicki...@gmail.com added the comment: Adding Meador Inge to nosy. -- nosy: +minge ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue8300 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue8300] Allow struct.pack to handle objects with an __index__ method.
Mark Dickinson dicki...@gmail.com added the comment: That patch was a bit hasty in many respects; here's a better one. For 2.7, the scheme is as follows: when packing a non-integer with an integer format: (1) First __index__ is tried (2) If the __index__ method doesn't exist, or the call to __index__ raises TypeError, then the __int__ method is tried. (3) If the __index__ method raises something other than TypeError, or returns a non-integer, then struct.pack fails. -- Added file: http://bugs.python.org/file16748/struct_index_trunk2.patch ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue8300 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue8300] Allow struct.pack to handle objects with an __index__ method.
Changes by Mark Dickinson dicki...@gmail.com: -- priority: - normal stage: test needed - patch review ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue8300 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue8300] Allow struct.pack to handle objects with an __index__ method.
Mark Dickinson dicki...@gmail.com added the comment: Committed this patch to trunk in r79674. Will forward port to py3k. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue8300 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue8300] Allow struct.pack to handle objects with an __index__ method.
Meador Inge mead...@gmail.com added the comment: I may be missing something subtle, but how can 'PyNumber_Index(v) != NULL' *and* '!PyInt_Check(v) !PyLong_Check(v)' both be satisfied in the 'get_pylong' mods? It seems to me that 'PyNumber_Index' only returns non-NULL when the object being returned is an 'int' or 'long'. Attached a patch with the extra check removed and a few more test cases. -- Added file: http://bugs.python.org/file16751/struct_index_trunk3.patch ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue8300 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
