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.
    }

    // ----------------------------------------------------------------------------------------