How can I programmatically change the argspec of a function in a python decorator?

Question

Given a function:

def func(f1, kw=\'default\'):
    pass
bare_argspec = inspect.getargspec(func)

@decorator
def func2(f1, kw=\'default\'):
    pass
decorate         


        

Answer 1

There's the decorator module:

from decorator import decorator
@decorator
def trace(func, *args, **kw):
    print 'calling', func, 'with', args, kw
    return func(*args, **kw)

That makes trace a decorator with the same argspecs as the decorated function. Example:

>>> @trace
... def f(x, y=1, z=2, *args, **kw):
...     pass

>>> f(0, 3)
calling f with (0, 3, 2), {}

>>> from inspect import getargspec
>>> print getargspec(f)
ArgSpec(args=['x', 'y', 'z'], varargs='args', keywords='kw', defaults=(1, 2))