Created
October 4, 2020 19:41
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Dirty tricks to automatically inject keyword arguments from the caller's scope
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| """ | |
| Dirty tricks to automatically inject keyword arguments from the caller's scope. | |
| """ | |
| import functools | |
| import inspect | |
| import sys | |
| def auto_inject_kwargs(f): | |
| """ | |
| Decorator to automatically inject missing keyword arguments. | |
| The values are looked up by inspecting the caller's local variables of the | |
| same name. | |
| """ | |
| signature = inspect.getfullargspec(f) | |
| injectable_kwargs = set(signature.kwonlyargs) | |
| if signature.kwonlydefaults is not None: | |
| injectable_kwargs.difference_update(signature.kwonlydefaults.keys()) | |
| @functools.wraps(f) | |
| def wrapper(*args, **kwargs): | |
| missing_kwarg_names = injectable_kwargs.difference(kwargs.keys()) | |
| frame = sys._getframe(1) | |
| for name in missing_kwarg_names: | |
| if name in frame.f_locals: | |
| kwargs[name] = frame.f_locals[name] | |
| return f(*args, **kwargs) | |
| return wrapper | |
| def test_auto_inject_kwargs(): | |
| @auto_inject_kwargs | |
| def foo(a, *, b, c, d=4): | |
| return (a, b, c, d) | |
| c = 3 # Should be used b/c not present in call below. | |
| d = 5 # Should not be used b/c default value. | |
| actual = foo(1, b=2) | |
| expected = (1, 2, 3, 4) | |
| assert actual == expected |
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