How to pass function to class with specific arguments?

Question

I like to pass a function which has 2 arguments to a class where 1 of the arguments are "predefined". When I call the function from within a class instance, I only want to give the second variable (because I already defined the first). Example:

def my_fun(a, b):
    return a+b

class MyClass():
    def __init__(self, fun):
        self._fun = fun

    def class_function(self, c):
        return self._fun(c)


instance = MyClass(my_fun(a=5.0))
print(instance.class_function(10.0))

Is this possible?

Answer 1

Use partial from functools module.

from functools import partial


def my_fun(a, b):
    return a + b


class MyClass():
    def __init__(self, fun):
        self._fun = fun

    def class_function(self, c):
        return self._fun(c)


instance = MyClass(partial(my_fun, 5.0))
print(instance.class_function(10.0))