How to hide an implementation helper template?

Question

Suppose that I have two template functions declared in a header file:

template  void func1(const T& value);
template          


        

Answer 1

Since the user of your code needs to see the full definition of the func1 function, it's implementation, nor it's helper function implementation, can be hidden.

But if you move the implementation into another file, the user will only have to be confronted with the template declaration:

//templates.h
template< typename T > void f1( T& );

#include  // post-inclusion

And the definition:

// templates_impl.h
template< typename T > void f1_helper( T& ) {
}

template< typename T > void f1( T& ) {
   // the function body
}