def __getitem__(cls, arg_types):
if not isinstance(arg_types, tuple):
arg_types = (arg_types,)
assert not any(isvariadic(arg_type) for arg_type in arg_types), "nested variadic types not supported"
# switch tuple to typing.Tuple
arg_types = tuple(typing.Tuple if arg_type is tuple else arg_type for arg_type in arg_types)
if arg_types not in cls._type_cache:
assert not cls.__args__, "cannot subscript a subscripted type {}".format(cls)
assert len(arg_types) == len(cls._ast_fields), "must provide types for all params"
new_dct = cls.__dict__.copy()
new_dct.update({"__args__": arg_types})
# type(cls) to handle FunsorMeta subclasses
cls._type_cache[arg_types] = type(cls)(cls.__name__, (cls,), new_dct)
return cls._type_cache[arg_types]
def get_first_occurrence(self, *types):
"""
Returns the first occurrence of a matching function
Based on `multipledispatch.Dispatcher.dispatch_iter`, which
returns an iterator of matching functions. This method uses
the same logic to select functions, but simply returns the first
element of the iterator. If no matching functions are found,
`None` is returned.
"""
n = len(types)
for signature in self.ordering:
if len(signature) == n and all(map(issubclass, types, signature)):
result = self.funcs[signature]
return result
elif len(signature) and isvariadic(signature[-1]):
if variadic_signature_matches(types, signature):
result = self.funcs[signature]
return result
return None
def test_is_variadic():
assert isvariadic(Variadic[A])
assert not isvariadic(A)