Give function defaults arguments from a dictionary in Python

Question

Let\'s imagine I have a dict :

d = {\'a\': 3, \'b\':4}

I want to create a function f that does the exact same thing than this function :

Answer 1

This question is very interesting, and it seemed different people have their different own guess about what the question really want.

I have my own too. Here is my code, which can express myself:

# python3 only
from collections import defaultdict

# only set once when function definition is executed
def kwdefault_decorator(default_dict):
    def wrapper(f):
        f.__kwdefaults__ = {}
        f_code = f.__code__
        po_arg_count = f_code.co_argcount
        keys = f_code.co_varnames[po_arg_count : po_arg_count + f_code.co_kwonlyargcount]
        for k in keys:
            f.__kwdefaults__[k] = default_dict[k]
        return f

    return wrapper

default_dict = defaultdict(lambda: "default_value")
default_dict["a"] = "a"
default_dict["m"] = "m"

@kwdefault_decorator(default_dict)
def foo(x, *, a, b):
    foo_local = "foo"
    print(x, a, b, foo_local)

@kwdefault_decorator(default_dict)
def bar(x, *, m, n):
    bar_local = "bar"
    print(x, m, n, bar_local)

foo(1)
bar(1)
# only kw_arg permitted
foo(1, a=100, b=100)
bar(1, m=100, n=100)

output:

1 a default_value
1 m default_value
1 100 100
1 100 100