generic functions with @generic #86
Description
pep-695 doesn't address specifying type vars on generic function calls or the reification of generic parameters. What about something like the following:
from basedtyping import generic
@generic
def foo[T](t: T) -> T:
return t
foo[object](1)
@generic
def bar[T](type_vars, t: T) -> T:
if issubclass(type_vars.T, int):
return t + 1
return t
print(bar[object](1)) # 1
print(bar[int](1)) # 2and an impl like:
Details
import dataclasses
import inspect
from typing import Callable
@dataclasses.dataclass
class Args:
_args: object
_params: object
def __getattr__(self, attr):
for i, arg in enumerate(self._params):
if arg.__name__ == attr:
return self._args[i]
super().__getattribute__(attr)
@dataclasses.dataclass
class GenericFunction:
fn: Callable
args: tuple = ()
def __call__(self, *args, **kwargs):
if tuple(inspect.signature(self.fn).parameters.keys())[0] == "type_vars":
if not self.args:
raise TypeError("You have to supply the args...")
return self.fn(self.args, *args, **kwargs)
self.fn(*args, **kwargs)
def __getitem__(self, item):
if not isinstance(item, tuple):
item = (item,)
return GenericFunction(self.fn, Args(item, self.fn.__type_params__))
def generic(fn: Fn) -> GenericFunction:
return GenericFunction(fn)