New submission from Marc Guetg:
At the moment it is only possible to combine flags that already exist:
from enum import *
class Foo(Flag):
A = auto() # 1
B = auto() # 2
AB = A | B # 3 (1 | 2)
AC = auto() | A # Fails, but should be 5 (1 | 4)
ABD = auto() | A | B # Just taking it one step further to make a point, 11
(1 | 2 | 8)
It would be nice to have this for cases when C only makes sense in combination
with A but not on its own.
A solution to achieve this one would need to change two things in
~/cpython/Lib/enum.py
First extend class auto by:
class auto:
"""
Instances are replaced with an appropriate value in Enum class suites.
"""
value = _auto_null
or_value = 0
def __or__(self, other):
""" Postpone the real or operation until value creation in _EnumDict """
self.or_value |= other
return self
And second change one line in _EnumDict:
value = value.value
changes to:
value = value.value | value.or_value
Some simple tests show the expected results:
print(repr(Foo.A)) # A - 1
print(repr(Foo.B)) # B - 2
print(repr(Foo.AB)) # AB - 3
print(repr(Foo.AC)) # AC - 5
print(repr(Foo.A | Foo.AC)) # AC - 5
print(repr(Foo.A & Foo.AC)) # A - 1
print(repr(Foo.ABD)) # ABD - 11
Would it make sense to enhance python enums with that functionality?
----------
components: Library (Lib)
files: test.py
messages: 288029
nosy: magu
priority: normal
severity: normal
status: open
title: implement __or__ in enum.auto
type: enhancement
versions: Python 3.6, Python 3.7
Added file: http://bugs.python.org/file46646/test.py
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Python tracker <rep...@bugs.python.org>
<http://bugs.python.org/issue29594>
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