Add a gi_code attr to generators

[collinwinter]

BPO	1473257
Nosy	@gvanrossum, @birkenfeld, @pjeby
Files	gi_code.patch: Add gi_code attr to generators, against r46040 NEWS.diff: Add an item to Misc/NEWS about the gi_code attr, against r46040

^{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/birkenfeld'
closed_at = <Date 2008-01-26.14:14:40.316>
created_at = <Date 2006-04-19.21:39:28.000>
labels = ['interpreter-core']
title = 'Add a gi_code attr to generators'
updated_at = <Date 2008-01-26.14:14:40.315>
user = 'https://bugs.python.org/collinwinter'

bugs.python.org fields:

activity = <Date 2008-01-26.14:14:40.315>
actor = 'georg.brandl'
assignee = 'georg.brandl'
closed = True
closed_date = <Date 2008-01-26.14:14:40.316>
closer = 'georg.brandl'
components = ['Interpreter Core']
creation = <Date 2006-04-19.21:39:28.000>
creator = 'collinwinter'
dependencies = []
files = ['7185', '7186']
hgrepos = []
issue_num = 1473257
keywords = ['patch']
message_count = 7.0
messages = ['50081', '50082', '50083', '50084', '61270', '61476', '61710']
nosy_count = 4.0
nosy_names = ['gvanrossum', 'georg.brandl', 'collinwinter', 'pje']
pr_nums = []
priority = 'normal'
resolution = 'accepted'
stage = None
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue1473257'
versions = ['Python 2.6']

[collinwinter]

In the test suite for one of my packages, I've used
something like gen.gi_frame.f_code.co_name to help make
human-readable assertions about when certain generators
are run deep inside the application. This was possible
because Python 2.4 guaranteed that gi_frame was always
a frame instance, even after the generator exhausted
itself. In Python 2.5, however, gi_frame is None when
the generator has run till exhaustion, meaning that I
can't always get to f_code.co_name.

I'd like to add a gi_code attribute to generators that
would allow users to access the code object behind the
generator, even when gi_frame is None. This attribute
would be read-only and would follow this rule:

>>> def f():
...     yield 5
...
>>> g = f()
>>> g.gi_code is f.func_code
True
>>>

The attached patch (against r45570) implements the
proposed attribute (in Include/genobject.h and
Objects/genobject.c) and adds test cases to
Lib/test/test_generators.py for this attribute.

[collinwinter]

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I've updated the patch; it's now against SVN r45808.

[birkenfeld]

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user_id=849994

Phillip, do you have an opinion on this one?

[collinwinter]

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user_id=1344176

In addition to updating the main patch to r46040, I've
included a diff against Misc/NEWS to make mention of the
gi_code attribute.

Any thoughts on getting this into 2.5a3?

[birkenfeld]

Guido, do you have an opinion? Seems like a nonproblematic and probably
useful change for 2.6.

[gvanrossum]

I noticed some whitespace issues in the patch, but apart from that I
have no objection. (Not any particular enthusiasm, I have to admit -- I
don't quite get the use case, but as Georg remarks, it seems harmless.)

[birkenfeld]

Reformatted the patch to use tabs and committed as r60324.