Passing SOME of the parameters to a function in python

Question

Let's say I have:

def foo(my_num, my_string):
    ...

And I want to dynamically create a function (something like a lambba) that already has my_string, and I only have to pass it my_num:

foo2 = ??(foo)('my_string_example')
foo2(5)
foo2(7)

Is there a way to do that?

Answer 1

This is what functools.partial would help with:

from functools import partial

foo2 = partial(foo, my_string="my_string_example")

Demo:

>>> from functools import partial
>>> def foo(my_num, my_string):
...     print(my_num, my_string)
... 
>>> foo2 = partial(foo, my_string="my_string_example")
>>> foo2(10)
(10, 'my_string_example')
>>> foo2(30)
(30, 'my_string_example')

Answer 2

This should do it:

>>> def foo(a, b):
...    return a+b
...
>>> def makefoo2(a):
...    def f(b):
...        return foo(a,b)
...    return f
...
>>> foo2 = makefoo2(3)
>>> foo2(1)
4

Obviously you can vary the definition of foo to taste.