Access default function argument values by name/identifier

Question

Consider the following simplified example:

def f(string, offset=0):
    print(string[offset:] if isinstance(offset, int) else string[f.__defaults__[0]:])

f('Hello', 'two')

While the tuple returned by f.__defaults__ gives access to all default argument values in the respective order (i. e. by position), I wonder if there is a way to access them by name/identifier of the argument (here: 'offset') from within the function ...

Answer 1

You can use inspect.signature to obtain the parameters of a given function, from which mapping you can get the default value of a named parameter:

import inspect

def f(string, offset=0):
    print(string[offset:] if isinstance(offset, int) else string[f_params['offset'].default:])

f_params = inspect.signature(f).parameters