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Simple python3k function annotation enforcer
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| #!/usr/bin/python3 | |
| """ | |
| Pure-Python 3 function annotation enforcer. | |
| @author Pedro Rittner | |
| """ | |
| from functools import wraps | |
| from inspect import getcallargs | |
| def enforce_annotations(fun): | |
| """ | |
| Function annotation to enforce function argument and return types. | |
| """ | |
| @wraps(fun) | |
| def _wrapper(*args, **kwargs): | |
| """ Check each annotated argument type for type correctness """ | |
| for arg, val in getcallargs(fun, *args, **kwargs).items(): | |
| if arg in fun.__annotations__: | |
| templ = fun.__annotations__[arg] | |
| msg_args = {'arg': arg, 'f': fun, 't1': type(val), 't2': templ} | |
| msg = """Argument mismatch in call to {f}: | |
| \'{arg}\' is of type {t1}, expected type {t2}""" | |
| if val is not None and not issubclass(val.__class__, templ): | |
| raise TypeError(msg.format(**msg_args)) | |
| # Call wrapped function and get return value | |
| return_val = fun(*args, **kwargs) | |
| if 'return' in fun.__annotations__: | |
| templ = fun.__annotations__['return'] | |
| msg_args = {'f': fun, 't1': type(return_val), 't2': templ} | |
| msg = """Return type mismatch in call to {f}: | |
| Call return type {t1} does not match expected type {t2}""" | |
| if (return_val is not None | |
| and not issubclass(return_val.__class__, templ)): | |
| raise TypeError(msg.format(**msg_args)) | |
| return return_val | |
| return _wrapper | |
| @enforce_annotations | |
| def dummy_function(a: int, b: float=0, s: str=None) -> str: | |
| return s + str(a + b) | |
| def main(): | |
| # This works | |
| print(dummy_function(5, 6.0, "lol")) | |
| # This will not | |
| print(dummy_function(5.0, 6, 7)) | |
| if __name__ == ""__main__": | |
| main() |
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