staticmethod and classmethod are ignored when disassemble class

[zhangyangyu]

BPO	26733
Nosy	@ncoghlan, @serhiy-storchaka, @1st1, @zhangyangyu
Files	add_staticmethod_and_classmethod_when_dis.dis_a_class.patch add_staticmethod_and_classmethod_when_dis.dis_a_class_v2.patch add_staticmethod_and_classmethod_when_dis.dis_a_class_v3.patch add_staticmethod_and_classmethod_when_dis.dis_a_class_v4.patch add_staticmethod_and_classmethod_when_dis.dis_a_class_v5.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/serhiy-storchaka'
closed_at = <Date 2016-04-23.06:25:52.452>
created_at = <Date 2016-04-11.10:19:34.128>
labels = ['type-bug', 'library']
title = 'staticmethod and classmethod are ignored when disassemble class'
updated_at = <Date 2016-04-23.06:25:52.451>
user = 'https://github.com/zhangyangyu'

bugs.python.org fields:

activity = <Date 2016-04-23.06:25:52.451>
actor = 'serhiy.storchaka'
assignee = 'serhiy.storchaka'
closed = True
closed_date = <Date 2016-04-23.06:25:52.452>
closer = 'serhiy.storchaka'
components = ['Library (Lib)']
creation = <Date 2016-04-11.10:19:34.128>
creator = 'xiang.zhang'
dependencies = []
files = ['42429', '42430', '42431', '42439', '42442']
hgrepos = []
issue_num = 26733
keywords = ['patch']
message_count = 12.0
messages = ['263176', '263178', '263187', '263220', '263221', '263224', '263226', '263233', '263627', '263643', '264046', '264047']
nosy_count = 5.0
nosy_names = ['ncoghlan', 'python-dev', 'serhiy.storchaka', 'yselivanov', 'xiang.zhang']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue26733'
versions = ['Python 3.5', 'Python 3.6']

[zhangyangyu]

Though the documentation tells when disassembling a class, it disassembles all methods for dis.dis, but staticmethod and classmethod are ignored. I don't know whether this is intended.

I write to patch to add staticmethod and classmethod. But unfortunately when I write tests, one unrelated test fails and I cannot figure out why.

[zhangyangyu]

Though don't know why but simply replace %-4d with %3d in dis_bug708901 can fix the test. I updated the patch so all the tests pass and then I'll spend some time figuring out why.

[zhangyangyu]

After researching the code, I think changing ' %-4d' to '%3d' in dis_bug708901 is right. Since I added some some lines and the lineno of test_bug708901 has arrived at 100+ and the leading space should not be there. According to the code of dis.dis, the right format string should be '%3d'. Not only test_bug708901, all the other ' %-4d' should be changed to '%3d'. If we add 1000+ lines at the head of the file, then all the ' %-4d' format string will lead to test failures.

I update my patch.

[ncoghlan]

The code and test changes in the latest patch look good to me. For documentation, I suggest updating https://docs.python.org/3/library/dis.html#dis.dis to:

• say "it disassembles all methods (including class and static methods)" when describing how classes are handled.

• add a version changed note for 3.6 to say that class and static methods are disassembled in addition to normal instance methods when disassembling a class

[zhangyangyu]

I update the documentation. Learning from devguide, the change of whatsnew is the committer's work. ;)

[serhiy-storchaka]

If this is new feature, perhaps the docs need the versionchanged directive. Otherwise the patch should be applied to all maintained branches.

Added other comments on Rietveld.

[python-dev]

New changeset b114a0650c44 by Serhiy Storchaka in branch '3.5':
Issue bpo-26733: Fixed formatting line numbers in test_dis.
https://hg.python.org/cpython/rev/b114a0650c44

New changeset e0816ce68952 by Serhiy Storchaka in branch 'default':
Issue bpo-26733: Fixed formatting line numbers in test_dis.
https://hg.python.org/cpython/rev/e0816ce68952

New changeset 16a27e38e9b5 by Serhiy Storchaka in branch '2.7':
Issue bpo-26733: Fixed formatting line numbers in test_dis.
https://hg.python.org/cpython/rev/16a27e38e9b5

[zhangyangyu]

Thanks for your comments Serhiy. I update the patch according to your comments.

Actually I don't think this is a new feature. Maybe staticmethod and classmethod are just forgotten.

As for separate tests for staticmethod and classmethod, I think they are not needed for this patch since right now we can use dis.dis to disassemble them explicitly. Only when dis.dis a class they are missing. But since there are no tests for them, adding tests for them is good.

[serhiy-storchaka]

LGTM.

Nick, do you consider this as a new feature, or as a fix?

[ncoghlan]

Looking at the history of the dis module, I'd now class this as a bug fix for 3.5+ - it looks like dis.dis gained the ability to disassemble static and class methods as a side-effect of the removal of bound methods in Python 3 (see https://hg.python.org/cpython/rev/48af6375207e ) but because it was a side effect, the additional changes needed to also handle them when disassembling a class were missed.

[python-dev]

New changeset d14ea3964590 by Serhiy Storchaka in branch '3.5':
Issue bpo-26733: Disassembling a class now disassembles class and static methods.
https://hg.python.org/cpython/rev/d14ea3964590

New changeset f96fec10cf25 by Serhiy Storchaka in branch 'default':
Issue bpo-26733: Disassembling a class now disassembles class and static methods.
https://hg.python.org/cpython/rev/f96fec10cf25

[serhiy-storchaka]

Thank you for your contribution Xiang Zhang.