Question

If I have a non-template (i.e. ‘normal’) class and wish to have a template friend function, how do I write it without causing a compiler error? Here is an example to illustrate what I am trying to do:

template <class T> void bar(T* ptr);  class MyClass  // note that this isn't a template class { private:     void foo();      template <class T>     friend void bar(T*);  // ERROR: compiler gives me all kinds of grief };  template <class T> void bar(T* ptr) {     if (ptr)     {         MyClass obj;          obj.foo();     } } 

I’m using Visual Studio 2005, and the specific error I’m given is error C2063, stating that ‘bar’ isn’t a function. What needs to be done differently here?

Answer 1

Are you sure what you’ve posted gives the error? The following (using Visual Studio 2005) works fine for me:

#include <iostream> template <class T> void bar(T* ptr);  class MyClass  // note that this isn't a template class { private:     void foo();      template <class T>     friend void bar(T*);  // ERROR: compiler gives me all kinds of grief };  void MyClass::foo() {     std::cout << 'fooed!' << std::endl; }  template <class T> void bar(T* ptr) {     if (ptr)     {         MyClass obj;          obj.foo();     } }   int _tmain(int argc, _TCHAR* argv[]) {      int someObj = 1;     bar(&someObj);      return 0; }