dlib C++ Library - member_function_pointer_ex.cpp

// The contents of this file are in the public domain. See LICENSE_FOR_EXAMPLE_PROGRAMS.txt
/*
 This is an example illustrating the use of the member_function_pointer object 
 from the dlib C++ Library.
*/
#include <iostream>
#include <dlib/member_function_pointer.h>
using namespace dlib;
using namespace std;
// ----------------------------------------------------------------------------------------
class example_object 
{
public:
 void do_something (
 )
 {
 cout << "hello world" << endl;
 }
 void print_this_number (
 int num
 )
 {
 cout << "number you gave me = " << num << endl;
 }
};
// ----------------------------------------------------------------------------------------
int main()
{
 // create a pointer that can point to member functions that take no arguments
 member_function_pointer<> mfp1;
 // create a pointer that can point to member functions that take a single int argument
 member_function_pointer<int> mfp2;
 example_object obj;
 // now we set the mfp1 pointer to point to the member function do_something() 
 // on the obj object.
 mfp1.set(obj, &example_object::do_something);
 // now we set the mfp1 pointer to point to the member function print_this_number() 
 // on the obj object.
 mfp2.set(obj, &example_object::print_this_number);
 // Now we can call the function this pointer points to. This calls the function
 // obj.do_something() via our member function pointer.
 mfp1();
 // Now we can call the function this pointer points to. This calls the function
 // obj.print_this_number(5) via our member function pointer.
 mfp2(5);
 // The above example shows a very simple use of the member_function_pointer. 
 // A more interesting use of the member_function_pointer is in the implementation
 // of callbacks or event handlers. For example, when you register an event
 // handler for a dlib::button click it uses a member_function_pointer 
 // internally to save and later call your event handler. 
}
// ----------------------------------------------------------------------------------------