CODEWITHSUNDEEP
pythonc++functional-programming
user69453
user69453

Reputation: 1405

Is there a C++ equivalent to python's functools.partial

I really like the functools.partial function in python and the idea of this functionallity in general. As example consider the following python script (I know that this case is not a very usefull example für using functools.partial, it should just be an easy example.)

import functools

def func(a, b, c):
    sum = a + b + c
    return sum


if __name__ == "__main__":
    func_p = functools.partial(func, a=1, c=1)
    sum = func_p(b=1)
    print(sum)

Is there something in C++ which offers a similar functionallity?

Upvotes: 3

Views: 2132

Answers (2)

Ami Tavory
Ami Tavory

Reputation: 76336

Yes, lambda functions:

auto func_p = [](int b){return func(1, b, 1);};

func_p(1);

Incidentally, I personally prefer lambdas in Python too. Consider the following:

lambda b: func(b**2, b, b - 3)

which can't be done with functools. Why have two different solutions (one applicable only in certain instances)?

There should be one-- and preferably only one --obvious way to do it.

Upvotes: 9

Lingxi
Lingxi

Reputation: 14987

A similar facility in C++ may be std::bind. See the following code for an illustration:

#include <functional>
#include <iostream>

int func(int a, int b, int c) {
  return a + b + c;
}

int main() {
  auto func_p = std::bind(func, 1, std::placeholders::_1, 1);
  std::cout << func_p(1) << std::endl;
}

Upvotes: 5

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