Created
July 24, 2017 15:59
-
-
Save onionka/bdd555c4616546b3571c5e94b36eead8 to your computer and use it in GitHub Desktop.
Implementation of instance function overloading achieved with annotations and inspect
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| import inspect | |
| class Overloadable(object): | |
| def __init__(self, fn): | |
| self.base = fn | |
| self.overloads = (fn, inspect.signature(fn).parameters), | |
| self.instance = None | |
| def overload(self, fn): | |
| self.overloads += (fn, inspect.signature(fn).parameters), | |
| return self | |
| def __call__(self, *args, **kwargs): | |
| _args = tuple((None, a) for a in args) | |
| for fn, o in self.overloads: | |
| try: | |
| overloaded_params = tuple(o.items()) | |
| params = _args + tuple(kwargs.items()) | |
| assert len(params) == len(overloaded_params) - 1 | |
| for (sn, st), (rn, rt) in zip(overloaded_params[1:], params): | |
| assert isinstance(rt, st.annotation) | |
| return fn(self.parent_object, *args, **kwargs) | |
| except AssertionError as ex: | |
| pass | |
| raise NotImplemented("this kind of overload is not implemented") | |
| def __get__(self, instance, owner): | |
| self.parent_object = instance | |
| return self | |
| def overloadable(fn): | |
| return Overloadable(fn) |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment