Question

Let’s say we have a class called A and another one called B.
and we want to have a conversion method that converts A to B.

In the software architecture point of view, which one is preferred?

1. write A.export()
2. write B.import()
3. write a converter class, i.e. convert(A, B) or Convert(A) or …

if the language matters, I’m using C++

Answer 1

It entirely depends on how you intend to use it, but in many cases, the cleanest way to do this is to implement a converting constructor:

class B { };
class A
{
    A(const B& b) { }
};

B b;
A a = b; //< calls converting constructor

(of course, you could implement a converting constructor for converting from A to B, as well)