Question

Suppose I had this.

class A {
  public:
    int f1();
    int f2();
}

Is there any way to use templates/macros/both to generate a class that behaves like the following?

class GeneratedClass {
  public:
    GeneratedClass(InjectedFunction injected_function) { /* store it */ }
    int f1() {
      injected_function();
      /* forward call to "inner class" and return its value */
    }
    int f2() {
      injected_function()
      /* forward call to "inner class" and return its value */
    }
}

Basically I want to be able to generate a class that supports all the functions of a given class, but doing something before it blindly forwards the call.

This class will be created with something like.

SomeClassTemplate<A> infected_a(injected_function);

Answer 1

No, templates cannot generate that code for you automatically. You must write it by hand.