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Line number of docstring in AST #74682
Description
| BPO | 30497 |
|---|---|
| Nosy | @vstinner, @methane, @serhiy-storchaka |
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 2017-05-29.17:41:19.169>
created_at = <Date 2017-05-28.18:44:26.274>
labels = ['interpreter-core', '3.7']
title = 'Line number of docstring in AST'
updated_at = <Date 2017-05-29.17:59:27.288>
user = 'https://bugs.python.org/myint'bugs.python.org fields:
activity = <Date 2017-05-29.17:59:27.288>
actor = 'myint'
assignee = 'none'
closed = True
closed_date = <Date 2017-05-29.17:41:19.169>
closer = 'serhiy.storchaka'
components = ['Interpreter Core']
creation = <Date 2017-05-28.18:44:26.274>
creator = 'myint'
dependencies = []
files = []
hgrepos = []
issue_num = 30497
keywords = []
message_count = 5.0
messages = ['294654', '294673', '294688', '294706', '294708']
nosy_count = 4.0
nosy_names = ['vstinner', 'methane', 'serhiy.storchaka', 'myint']
pr_nums = []
priority = 'normal'
resolution = 'wont fix'
stage = 'resolved'
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue30497'
versions = ['Python 3.7']
Activity
myint commentedon May 28, 2017
Since bpo-29463, it is no longer obvious how to get the line number of a docstring in the AST:
We use this feature in pyflakes (PyCQA/pyflakes#271).
serhiy-storchaka commentedon May 29, 2017
It is not possible anymore. Why you need the line number of a docstring?
The closest approximation is between node.lineno and node.body[0].lineno (if node.body is not empty).
vstinner commentedon May 29, 2017
AST is not designed to be 1-to-1 .py source to AST mapping. If you need the exact line number, you might use your own parser. I don't know what is using pylint for example? There is also https://github.com/PyCQA/redbaron which provides such 1-to-1 mapping but it has a different API than AST.
Sadly, I suggest to close this issue as WONTFIX.
serhiy-storchaka commentedon May 29, 2017
Even if the line number of a docstring is known, it is not easy to determine the line number corresponding to the particular line in a docstring if it contains backslashes following by newline.
'''foo
bar
'''
and
'''\
foo
bar
'''
are equal strings, but the lines 'bar' have different offsets from the start of the strings.
The only robust method was parsing the source code starting from the start of a docstring. Now you just need to start parsing from the start of the function/class.
myint commentedon May 29, 2017
I think what you guys have brought up makes sense.
Now that you mention it, I see that pyflakes gives the wrong line number if an escaped newline appears after the doctests. Though, it works fine if the escaped newline appears before it.
https://github.com/PyCQA/pyflakes/blob/1af4f14ad4675bf5c61c47bbb7c2421b50d1cba4/pyflakes/checker.py#L842
This is a non-default feature in pyflakes anyway, so we can live with it.
Thanks