Raymond Hettinger <[email protected]> added the comment:
FWIW, I discovered the issue when experimenting with ways to use the class
pattern in structural pattern matching.
--- Code that should work but doesn't -----------
class Warm:
def __instancecheck__(cls, inst):
return inst in {'red', 'orange', 'blue'}
match 'red':
case Warm(): # This doesn't match but should
print('Glowing')
--- What you have to do to get it to work -------
class MetaWarm(type):
def __instancecheck__(cls, inst):
return inst in {'red', 'orange', 'blue'}
class Warm(metaclass=MetaWarm):
pass
match 'red':
case Warm(): # This matches
print('Hot')
----------
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Python tracker <[email protected]>
<https://bugs.python.org/issue45791>
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