Pragma interface

One approach to controlling instantiation is to use #pragma in a program:

   #pragma instantiate A<int>  // template class name
   

   #pragma instantiate A<int>::f  // member function name
   

   #pragma instantiate A<int>::i  // static data member name
   

   #pragma instantiate void A<int>::f(int, char)
   	// member function declaration
   

   #pragma instantiate char* f(int, float)
   	// template function declaration

do_not_instantiate can be substituted for instantiate to exclude a specific member when instantiating a whole template class. For example,

   #pragma instantiate A<int>
   #pragma do_not_instantiate A<int>::f

Template definitions must be present in the source file (typically via an included header) for instantiation to occur. If an instantiation is explicitly requested via instantiate and no template definition is available or a specific definition is provided (a specialization), an error will be given.

   template <class T> void f1(T);  // No body provided
   template <class T> void g1(T);  // No body provided
   void f1(int) {}  // Specific definition
   int main()
   {
     int     i;
     double  d;
     f1(i);
     f1(d);
     g1(i);
     g1(d);
   }
   #pragma instantiate void f1(int) // error - specific definition
   #pragma instantiate void g1(int) // error - no body provided

You can specify overloaded functions by giving the complete member function declaration including all argument types. Inline and pure virtual functions cannot be instantiated.