I love the new modules feature of C++ 20, but , at least as far as G++ goes, it isn’t supported yet. While we wait for them to be an actual part, here is a small intro:

Cool thing number 1: we can use them to include files:

import <iostream>;
Code language: C++ (cpp)

This doesn’t seem like much, but now pch is included! Pretty awesome.

Cool thing number 2: Separate your work

//talreg.cppm
export module talreg;

namespace Talreg{
    int add(int x, int y){return x+y;}
    export int mul(int x, int y){return x*y;}
}

// main.cpp
import talreg;
import<iostream>
int main(){
    std::cout<<"3*4="<<mul(3,4)<<std::endl;
}
Code language: C++ (cpp)

You might want to notice the file extension – cppm.

Cool thing number 3: You don’t have to use header files

Admittedly, this might not be the right thing for huge modules, but it is still a great feature,