Decorator with paren tokens in arguments breaks inspect.getsource

@PCManticore

BPO	38854
Nosy	@PCManticore, @1st1, @tirkarthi, @crusaderky, @AlexWaygood, @ahopkins
PRs	bpo-38854: Adjust `inspect.getsource` to properly extract source for decorated functions #17374 bpo-46873: Fix inspect.getsource - Count parentheses open/close in decorators #31605

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

Show more details

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2019-11-19.21:37:42.431>
labels = ['type-bug', 'library', '3.9', '3.10']
title = 'Decorator with paren tokens in arguments breaks inspect.getsource'
updated_at = <Date 2022-02-28.11:08:51.171>
user = 'https://github.com/crusaderky'

bugs.python.org fields:

activity = <Date 2022-02-28.11:08:51.171>
actor = 'AlexWaygood'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2019-11-19.21:37:42.431>
creator = 'crusaderky'
dependencies = []
files = []
hgrepos = []
issue_num = 38854
keywords = ['patch']
message_count = 2.0
messages = ['356993', '357432']
nosy_count = 6.0
nosy_names = ['Claudiu.Popa', 'yselivanov', 'xtreak', 'crusaderky', 'AlexWaygood', 'ahopkins']
pr_nums = ['17374', '31605']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue38854'
versions = ['Python 3.9', 'Python 3.10']

Linked PRs

Python 3.7.5 and 3.8.0
A decorator causes inspect.getsource() to return clipped output:

from collections import defaultdict
from functools import wraps
import inspect


def foo(*args):
    def decorator(func):
        @wraps(func)
        def wrapper():
            pass
        return wrapper
    return decorator

@foo(dict(), defaultdict(lambda: 1))
def f():
    pass

print(inspect.getsource(f))

Output:

@foo(dict(), defaultdict(lambda: 1))

Expected output:

@foo(dict(), defaultdict(lambda: 1))
def f():
    pass

These changes to the decorator parameters cause the problem to disappear:

@foo({}, defaultdict(lambda: 1))
@foo(dict(), defaultdict(list))

Thanks for the report!

Turns out this was a bug in inspect.BlockFinder which is responsible for extracting out the source code from a given block. This class was considering ")" inside a decorator call as closing the decorator itself, even when the decorator call was accepting additional arguments that needed parentheses, such as function calls or tuples.

Just submitted a PR #17374 to address this issue.

pythongh-83035: handle decorator with nested parens in inspect.getsource

Looks like there have been three PRs here already, but all of them seem to be incomplete and/or abandoned. Opened a new one: #99654

gh-83035: handle decorator with nested parens in inspect.getsource (#…

pythongh-83035: handle decorator with nested parens in inspect.getsou…

gh-83035: handle decorator with nested parens in inspect.getsource (G…

@carljm

Fixed and backported. Thanks @carljm! 🎉

Navigation Menu

Repository navigation

Decorator with paren tokens in arguments breaks inspect.getsource #83035

Linked PRs

Metadata

Assignees

Labels

Projects

Milestone

Relationships

Development

Decorator with paren tokens in arguments breaks inspect.getsource #83035

Description

Linked PRs

Activity

crusaderky commented on Nov 19, 2019

PCManticore commented on Nov 25, 2019

carljm commented on Nov 21, 2022

AlexWaygood commented on Dec 7, 2022

Metadata

Metadata

Assignees

Labels

Projects

Milestone

Relationships

Development

Issue actions