Correctly implent large template class

[wizulis]

I have a large class, which can be used with multiple data structures. So - I made it a template class, but was struck with linking problems. Now I don't know which would be the best road to take to resolve these linking problems.

So a simple example:

//a.h
template<class T> class A
{
 T a;
 void print();
 T ret();
} 
//a.cpp
template<class T>void A<T>::print(){cout << a;}
template<class T>T A<T>::ret(){ return a;}


template void A<int>::print(){cout << a;}
template int A<int>::ret(){ return a;}

And the question:
Is it possible to implent a large class in a separate cpp file without

template void A<int>::print(){cout << a;}
template int A<int>::ret(){ return a;}

for each data type?

[Peter87]

No. You have to implement it in the header.

[wizulis]

Damn :( Looks like then it's simpler to use inheritance.

[Peter87]

Is it really a problem implementing the template in the header? Templates is a bit special so you can put the function implementations outside the class definition if you like. If you just want to have them in different files you could create a file that you include in the header file.

//a.h
template<class T> class A
{
 T a;
 void print();
 T ret();
} 
#include "a.impl"

//a.impl
template<class T>void A<T>::print(){cout << a;}
template<class T>T A<T>::ret(){ return a;}

[moorecm]

I believe you could also use explicit instantiation, if you know exactly what types the class template with be used with, but the inclusion model does not have that limitation.