c++ - How to link selected instantiation of templated class/function?

Lets say, I have 3 classes, that provides same functions. They are unrelated in class hierarchy but they are implemented in such way to be similar to eachother.

• class A


• class B


• class C

For example purposes lets assume that A, B and C are arrays that hold some integers, but every class holds it in different way. Every class provides its iterator class and class_name::begin() and class_name::end(). Now I have some function template foo that increments every element of the array.

template 
void foo(T & a)

{
    for(auto & element : a)
        element++;
}

But lets say that foo has enormously big body, that works for every type T as A, B, or C. How can I tell compiler:

I will use only foo, foo and foo. Let me move my function to .cpp file and link it.

The reason I am asking this is because templates are used to shorten code, that works for more than one compile-time-resolvable context. I don't want to write the same function inside .cpp file 3 times.