Sam Bishop <[email protected]> added the comment:
Would the enhancements to resolve this, by making singledispatch accept more
things, also resolve the AssertionError from functools.singledispatch when
passing it custom types, or should I raise this as a separate issue?
------------------------------------------------
from typing import NewType, List
from functools import singledispatch
@singledispatch
def fun(arg, verbose=False):
if verbose:
print("Let me just say,", end=" ")
print(arg)
MyType = NewType('MyType', List[int])
@fun.register
def _(arg: MyType , verbose=False):
if verbose:
print("Strength in numbers, eh?", end=" ")
print(arg)
---------------------------------------------------------------------------
AssertionError Traceback (most recent call last)
<ipython-input-49-e549104faa9a> in <module>
5
6 @fun.register
----> 7 def _(arg: MyType , verbose=False):
8 if verbose:
9 print("Strength in numbers, eh?", end=" ")
~/.pyenv/versions/3.7.0/lib/python3.7/functools.py in register(cls, func)
809 argname, cls = next(iter(get_type_hints(func).items()))
810 assert isinstance(cls, type), (
--> 811 f"Invalid annotation for {argname!r}. {cls!r} is not a
class."
812 )
813 registry[cls] = func
AssertionError: Invalid annotation for 'arg'. <function
NewType.<locals>.new_type at 0x10fcd7730> is not a class.
----------
nosy: +techdragon
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Python tracker <[email protected]>
<https://bugs.python.org/issue34498>
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