[Python-ideas] Idea: Deferred Default Arguments?

[Brice Parent]

It might be stupid, but how about solving this problem using the following:

from . import other_func, SomeClass

def my_func(a=other_func.defaults.a, b=other_func.defaults.b, 
c=SomeClass.some_method.defaults.c):
     ...

or
def my_func(a=None, b=None, c=None):  # or use some sentinel value 
instead of None
     if a is None:
         a = other_func.defaults.a
     if b is None:
         b = other_func.defaults.b
     if c is None:
         c = SomeClass.some_method.defaults.c
     ...

or even
def my_func(a=None, b=None, c=None):
     if a is None:
         a = default(other_func, "a")
     if b is None:
         b = default(other_func, "b")
     if c is None:
         c = default(SomeClass.some_method, "c")
      ...

I used *.defaults.* but it might be something else, as well as the 
function I named 'default' which might be anything else.

I prefer the first, as it's both short and easy to read, but I'm not 
sure about the implications about such a thing. And it probably has 
already been proposed for other use cases.
The second and third versions are more verbose, but probably easier to 
implement, specially the third which should already be doable using 
something like

import inspect

def default(function, argument):
     return inspect.signature(function).parameters[argument].default.