New submission from Maxwell <maxwell...@gmail.com>:
This is a really minor bug.
In enum.py the function _is_sunder(name) fails on empty string with an
IndexError.
As a result, attempting to create an Enum with an empty string fails.
>>> from enum import Enum
>>> Yay = Enum('Yay', ('', 'B', 'C'))
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "C:\Program Files\Python37\lib\enum.py", line 311, in __call__
return cls._create_(value, names, module=module, qualname=qualname,
type=type, start=start)
File "C:\Program Files\Python37\lib\enum.py", line 422, in _create_
classdict[member_name] = member_value
File "C:\Program Files\Python37\lib\enum.py", line 78, in __setitem__
if _is_sunder(key):
File "C:\Program Files\Python37\lib\enum.py", line 36, in _is_sunder
return (name[0] == name[-1] == '_' and
IndexError: string index out of range
>>>
Expected behavior is for it to not fail, as Enum accepts wierd strings. Example:
>>> from enum import Enum
>>> Yay = Enum('Yay', ('!', 'B', 'C'))
>>> getattr(Yay, '!')
<Yay.!: 1>
>>>
Transcript of lines 26 to 39 of enum.py:
def _is_dunder(name):
"""Returns True if a __dunder__ name, False otherwise."""
return (name[:2] == name[-2:] == '__' and
name[2:3] != '_' and
name[-3:-2] != '_' and
len(name) > 4)
def _is_sunder(name):
"""Returns True if a _sunder_ name, False otherwise."""
return (name[0] == name[-1] == '_' and
name[1:2] != '_' and
name[-2:-1] != '_' and
len(name) > 2)
Solution 1: Replace with:
def _is_dunder(name):
"""Returns True if a __dunder__ name, False otherwise."""
return (len(name) > 4 and
name[:2] == name[-2:] == '__' and
name[2] != '_' and
name[-3] != '_')
def _is_sunder(name):
"""Returns True if a _sunder_ name, False otherwise."""
return (len(name) > 2 and
name[0] == name[-1] == '_' and
name[1:2] != '_' and
name[-2:-1] != '_')
In this solution, function '_is_dunder' was also altered for consistency.
Altering '_is_dunder' is not necessary, though.
Solution 2: Replace with:
def _is_dunder(name):
"""Returns True if a __dunder__ name, False otherwise."""
return (name[:2] == name[-2:] == '__' and
name[2:3] != '_' and
name[-3:-2] != '_' and
len(name) > 4)
def _is_sunder(name):
"""Returns True if a _sunder_ name, False otherwise."""
return (name[:0] == name[-1:] == '_' and
name[1:2] != '_' and
name[-2:-1] != '_' and
len(name) > 2)
In this solution, function '_is_sunder' was altered to follow
the style used in function '_is_dunder'.
----------
components: Library (Lib)
messages: 334866
nosy: Maxpxt
priority: normal
severity: normal
status: open
title: '_is_sunder' function in 'enum' module fails on empty string
type: crash
versions: Python 3.7
_______________________________________
Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue35899>
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