module struct support for ssize_t and size_t

[MrJean1]

BPO	3163
Nosy	@loewis, @mdickinson, @pitrou, @skrah, @meadori
Files	struct_size_t.rev2.patch: revised patch struct_nn.patch struct_nn2.patch struct_nn3.patch struct_nn4.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 = None
closed_at = <Date 2011-10-06.13:31:55.192>
created_at = <Date 2008-06-21.18:05:48.427>
labels = ['type-feature', 'library']
title = 'module struct support for ssize_t and size_t'
updated_at = <Date 2011-10-06.13:31:55.191>
user = 'https://bugs.python.org/MrJean1'

bugs.python.org fields:

activity = <Date 2011-10-06.13:31:55.191>
actor = 'pitrou'
assignee = 'none'
closed = True
closed_date = <Date 2011-10-06.13:31:55.192>
closer = 'pitrou'
components = ['Library (Lib)']
creation = <Date 2008-06-21.18:05:48.427>
creator = 'MrJean1'
dependencies = []
files = ['10690', '23310', '23311', '23312', '23318']
hgrepos = []
issue_num = 3163
keywords = ['patch']
message_count = 20.0
messages = ['68528', '68530', '68531', '107799', '107800', '110313', '110330', '110385', '112867', '144885', '144886', '144888', '144891', '144892', '144893', '144936', '144950', '144978', '145009', '145010']
nosy_count = 7.0
nosy_names = ['loewis', 'mark.dickinson', 'pitrou', 'MrJean1', 'skrah', 'meador.inge', 'python-dev']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue3163'
versions = ['Python 3.3']

[MrJean1]

Attached is a (simplistic) patch for the struct module to support C types
ssize_t and size_t with format characters 'z' resp. 'Z'.

The patch updates Python 2.6b1 files Modules/_struct.c and
Doc/library/struct.rst.

Note, format character 'Z' is also proposed in PEP-3118 for C type complex
and that has to be something else, perhaps 'C'.

[loewis]

Now that Python 2.6 is in beta, new features should be deferred to 2.7.

[MrJean1]

Please ignore the first patch. Use the rev2 patch which includes an
update for test file Lib/test/test_struct.py as well.

[mdickinson]

The proposed addition seems reasonable to me, for native packing and unpacking.

For standard mode packing and unpacking, I don't see the point; we'd have to pick a standard size, which would almost certainly be either 4 or 8, and so would already be covered by either the 'iI' or the 'qQ' codes. So I'd suggest adding the size_t/ssize_t codes only for native mode, and leaving them unsupported for the standard modes.

[mdickinson]

To avoid clashing with PEP-3118, we could use 'n' and 'N' instead of 'z' and 'Z'.

[mdickinson]

Jean, if you're still around:

Do you still have interest in pursuing this?

[MrJean1]

Yes I am and I will get back to you on this after check my (old) notes.

/Jean

On Wed, Jul 14, 2010 at 12:08 PM, Mark Dickinson <report@bugs.python.org>wrote:

Mark Dickinson <dickinsm@gmail.com> added the comment:

Jean, if you're still around:

Do you still have interest in pursuing this?

----------

---

Python tracker <report@bugs.python.org>
<http://bugs.python.org/issue3163\>

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[MrJean1]

It would be sufficient to support size_t/ssize_t in native mode for my usage. The workaround I have been using is in this recipe

<http://code.activestate.com/recipes/546530/\>

in the function calcsize. That maps the 'z' and 'Z' format to either 'l', 'L' or 'P' for lack of anything better.

[mdickinson]

Okay; would you be interested in updating your patch?

[pitrou]

bpo-3163 is a duplicate.

[pitrou]

Ooops, I meant bpo-13098.

[pitrou]

Here is a patch.

[meadori]

Mostly LGTM. I have a few comments in rietveld.

[pitrou]

Thanks. I have answered one of your comments, and here is a new patch.

[pitrou]

New patch with cosmetic doc fix.

[meadori]

Found a few test case nits. Comments in rietveld.

[pitrou]

Thanks for the comments. Here is an updated patch.

[meadori]

No problem. This last version LGTM.

[python-dev]

New changeset db3e15017172 by Antoine Pitrou in branch 'default':
Issue bpo-3163: The struct module gets new format characters 'n' and 'N'
http://hg.python.org/cpython/rev/db3e15017172

[pitrou]

Thanks for the reviews!