inspect.signature() doesn't parse __text_signature__ containing a newline character · Issue #85267 · python/cpython · GitHub

BPO	41095
Nosy	@vstinner, @serhiy-storchaka, @1st1, @asottile
PRs	bpo-31938: Fix default-value signatures of several functions in the select module #21066

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 2020-06-23.22:26:29.252>
labels = ['library', '3.10']
title = "inspect.signature() doesn't parse __text_signature__ containing a newline character"
updated_at = <Date 2020-06-24.01:12:14.804>
user = 'https://github.com/vstinner'

bugs.python.org fields:

activity = <Date 2020-06-24.01:12:14.804>
actor = 'Anthony Sottile'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2020-06-23.22:26:29.252>
creator = 'vstinner'
dependencies = []
files = []
hgrepos = []
issue_num = 41095
keywords = ['patch']
message_count = 2.0
messages = ['372213', '372222']
nosy_count = 4.0
nosy_names = ['vstinner', 'serhiy.storchaka', 'yselivanov', 'Anthony Sottile']
pr_nums = ['21066']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = None
url = 'https://bugs.python.org/issue41095'
versions = ['Python 3.10']

PR: gh-85267: Improvements to inspect.signature __text_signature__ handling #98796

PR: [3.11] gh-85267: Improvements to inspect.signature __text_signature__ handling (GH-98796) #100392

PR: [3.10] gh-85267: Improvements to inspect.signature __text_signature__ handling (GH-98796) #100393

$ ./python
Python 3.10.0a0 (heads/unicode_latin1:40855c7064, Jun 24 2020, 00:20:07) 
>>> import select
>>> select.epoll.register.__text_signature__
'($self, /, fd,\n         eventmask=select.EPOLLIN | select.EPOLLPRI | select.EPOLLOUT)'

>>> import inspect
>>> inspect.signature(select.epoll.register)
<Signature (self, /, fd)>

=> eventmask parameter is gone!

Either signature() must raise an exception, or it must handle a __text_signature__ containing a newline character.

Issue spotted on bpo-31938 when fixing "./python -m pydoc select".

By the way, as expected, pydoc shows:

Help on method_descriptor in select.epoll:
---

$ ./python -m pydoc select.epoll.register

select.epoll.register = register(self, /, fd)
    Registers a new fd or raises an OSError if the fd is already registered.
(...)

Looking into this, it appears to be due to the default value and not due to the newline

I've stumbled upon two simplifications to the routines in inspect but not a fix for this

bpo-20684: Remove unused inspect._signature_get_bound_param #21100
gh-99815: remove unused 'invalid' sentinel value and code that checks for it in inspect.signature parsing #21104

the following code is hit because ast.literal_eval(...) fails for the |d expression:

cpython/Lib/inspect.py

Lines 2069 to 2070 in 2f9ada9

    
           if o is invalid: 
        
               return None

this causes the parameter to be skipped entirely

pythongh-85267: Improvements to inspect.signature __text_signature__ …

Sadly, I don't have the bandwidth to work on this issue, so I just close it.

Reopening as there's an active PR fixing this.

What is the active PR?

#98796

gh-85267: Improvements to inspect.signature __text_signature__ handli…

[3.11] pythongh-85267: Improvements to inspect.signature __text_signa…

[3.10] pythongh-85267: Improvements to inspect.signature __text_signa…

[3.11] gh-85267: Improvements to inspect.signature __text_signature__…

[3.10] gh-85267: Improvements to inspect.signature __text_signature__…

Merged main into regmachine branch (#50)

inspect.signature() doesn't parse __text_signature__ containing a newline character · Issue #85267 · python/cpython · GitHub

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inspect.signature() doesn't parse __text_signature__ containing a newline character #85267

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inspect.signature() doesn't parse __text_signature__ containing a newline character · Issue #85267 · python/cpython · GitHub

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inspect.signature() doesn't parse __text_signature__ containing a newline character #85267

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vstinner commented on Jun 23, 2020

asottile commented on Jun 24, 2020

vstinner commented on Nov 3, 2022

JelleZijlstra commented on Nov 8, 2022

vstinner commented on Nov 8, 2022

JelleZijlstra commented on Nov 8, 2022

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