Correct __sizeof__ support for struct

[serhiy-storchaka]

BPO	15402
Nosy	@loewis, @gpshead, @jcea, @mdickinson, @asvetlov, @skrah, @meadori, @serhiy-storchaka
Files	struct_sizeof-2.patch issue15402-redux-v1.patch

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = 'https://github.com/meadori'
closed_at = <Date 2012-07-29.03:36:54.728>
created_at = <Date 2012-07-20.06:49:25.897>
labels = ['type-bug', 'library']
title = 'Correct __sizeof__ support for struct'
updated_at = <Date 2012-07-29.03:36:54.727>
user = 'https://github.com/serhiy-storchaka'

bugs.python.org fields:

activity = <Date 2012-07-29.03:36:54.727>
actor = 'meador.inge'
assignee = 'meador.inge'
closed = True
closed_date = <Date 2012-07-29.03:36:54.728>
closer = 'meador.inge'
components = ['Library (Lib)']
creation = <Date 2012-07-20.06:49:25.897>
creator = 'serhiy.storchaka'
dependencies = []
files = ['26444', '26520']
hgrepos = []
issue_num = 15402
keywords = ['patch']
message_count = 40.0
messages = ['165902', '165936', '165945', '165946', '166125', '166226', '166227', '166228', '166231', '166232', '166235', '166250', '166252', '166257', '166354', '166363', '166371', '166372', '166380', '166384', '166389', '166391', '166393', '166405', '166433', '166434', '166435', '166454', '166456', '166457', '166458', '166460', '166485', '166508', '166511', '166517', '166518', '166636', '166664', '166709']
nosy_count = 9.0
nosy_names = ['loewis', 'gregory.p.smith', 'jcea', 'mark.dickinson', 'asvetlov', 'skrah', 'meador.inge', 'python-dev', 'serhiy.storchaka']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue15402'
versions = ['Python 2.7', 'Python 3.2', 'Python 3.3']

[serhiy-storchaka]

Here is a patch that implements __sizeof__ for struct.Struct.

See also bpo-14596.

[meadori]

Module a few cosmetic changes (variable names and doc string tweaks), the patch looks good. Having a correct answer for sys.getsizeof(struct.Struct('100B')) is definitely better. Per the documentation for 'sys.getsizeof' [1]:

"""
All built-in objects will return correct results, but this does not have to hold true for third-party extensions as it is implementation specific.
"""

If we consider extension modules as built-in objects, then this is a bug and should be fixed in 2.7, 3.2, and 3.3. If we don't, then the documentation for 'sys.getsizeof' should be adjusted and this patch should be applied after the default branch is unfrozen for enhancements.

[1] http://docs.python.org/library/sys.html

[jcea]

The patch is easy. I want this in 3.3.

Reluctant to touch 2.7 and 3.2, thought. I would be +0 to it.

[gpshead]

makes sense for 3.3 as i would consider it a bug.

i think it is reasonable for 2.7 and 3.2 as well, it is an actual bug that the value reported to getsizeof on struct.Struct is meaningless.

[asvetlov]

+1 for patch applying in 3.3 at least

[meadori]

OK, I will commit this sometime today.

[python-dev]

New changeset dbe7f39ff341 by Meador Inge in branch '2.7':
Issue bpo-15402: Add a __sizeof__ method to struct.Struct.
http://hg.python.org/cpython/rev/dbe7f39ff341

New changeset 3e7b517e1b68 by Meador Inge in branch '3.2':
Issue bpo-15402: Add a __sizeof__ method to struct.Struct.
http://hg.python.org/cpython/rev/3e7b517e1b68

New changeset 03063e718f5f by Meador Inge in branch 'default':
Issue bpo-15402: Add a __sizeof__ method to struct.Struct.
http://hg.python.org/cpython/rev/03063e718f5f

[meadori]

Thanks for the patch Serhiy!

[jcea]

We collide mid-air, Meador. I was just checking-in this :-). I have changed the tests to actually verify the changes :-). Also added to "Doc/ACKS.txt".

Could I suggest you to take care of issue bpo-15424 too?.

[python-dev]

New changeset b1d85a44f149 by Jesus Cea in branch '2.7':
Better test for Issue bpo-15402: Add a __sizeof__ method to struct.Struct
http://hg.python.org/cpython/rev/b1d85a44f149

New changeset 1911e192af0d by Jesus Cea in branch '3.2':
Better test for Issue bpo-15402: Add a __sizeof__ method to struct.Struct
http://hg.python.org/cpython/rev/1911e192af0d

New changeset b9a3ed1b14b9 by Jesus Cea in branch 'default':
MERGE: Better test for Issue bpo-15402: Add a __sizeof__ method to struct.Struct
http://hg.python.org/cpython/rev/b9a3ed1b14b9

[meadori]

Hi Jesús,

I replied to python-dev, but the Doc/ACKS.txt changes aren't necessary and I was OK with the way Serhiy submitted the tests.