Enhance Cmd support for docstrings and document it.

[bitdancer]

BPO	7913
Nosy	@merwok, @bitdancer, @durban, @serhiy-storchaka
Files	cmd_doctest_enhancement.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 = None
created_at = <Date 2010-02-11.18:57:20.772>
labels = ['3.7', 'type-feature', 'library']
title = 'Enhance Cmd support for docstrings and document it.'
updated_at = <Date 2017-03-26.10:12:56.047>
user = 'https://github.com/bitdancer'

bugs.python.org fields:

activity = <Date 2017-03-26.10:12:56.047>
actor = 'serhiy.storchaka'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2010-02-11.18:57:20.772>
creator = 'r.david.murray'
dependencies = []
files = ['16213']
hgrepos = []
issue_num = 7913
keywords = ['patch']
message_count = 7.0
messages = ['99233', '101837', '101843', '101844', '131485', '131502', '290520']
nosy_count = 4.0
nosy_names = ['eric.araujo', 'r.david.murray', 'daniel.urban', 'serhiy.storchaka']
pr_nums = []
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue7913'
versions = ['Python 3.7']

Linked PRs

• gh-52161: Enhance Cmd support for docstrings #110987

[bitdancer]

Cmd currently has undocumented support for using the docstrings of 'do_' methods as the documentation for those methods. This is a very convenient facility, except that it leads to documentation being printed with a lot of leading whitespace.

I propose to enhance the docstring support to strip the leading whitespace from the docstring, and to document this facility. The proposed stripping algorithm is to strip a number of characters equal to the whitespace on the first non-blank line of the docstring. This means that existing docstrings, which will typically start right after the first """, will be displayed as they were previously, but that a docstring can be formatted by starting the documentation on a new line after the """, and whitespace will be properly stripped.

Patch attached with test and documentation update.

[merwok]

Hello

This would be a nice improvement. This weakness is indeed mentioned on PyMotW.

How about using textwrap.dedent?

Regards

[bitdancer]

The problem with using textwrap is that you'd have to identify paragraph boundaries and example code to avoid messing up the meaning of the doc string. At that point, one might as well go for full ReST markup parsing, and I don't think that is appropriate :)

[merwok]

The problem with using textwrap is that you'd have to identify paragraph boundaries
and example code to avoid messing up the meaning of the doc string.

I thought dedent just worked. Can you provide a simple example to help
me understand this problem?

Does this help:
http://code.activestate.com/recipes/358228-extend-textwraptextwrapper-to-handle-multiple-para/

Regards

[durban]

inspect.cleandoc (which is also used by inspect.getdoc and pydoc.getdoc) seems to do a similar thing. Maybe that could be used for this?

[merwok]

You can apply the patch (which includes tests) and edit the code of cmd.py to use cleandoc.

[serhiy-storchaka]

Can you create a pull request David?

[fipachu]

ping