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C-/C++-Quelltext

 derived() : m_int(0) { register_message(AE_RENDER, &derived::on_render); }

C-/C++-Quelltext

struct uncopyable
{
protected:
    uncopyable() {}
    ~uncopyable() {}

private:
    uncopyable( const uncopyable& );
    uncopyable& operator=( const uncopyable& );
};

struct base : protected uncopyable
{
    typedef void ( base::*memfun_ptr )( const void* );

    typedef std::map< std::size_t, memfun_ptr > list_type;
    typedef list_type::iterator iterator_type;

    static base* create()
    {
        static int instances = 0;

        assert( !( instances++ ) && "zu viele instanzen" );

        static base inst;
        return &inst;
    }
    
    void register_msg( std::size_t id, memfun_ptr handler )
    {
        list[ id ] = handler;
    }

    void call_msg( std::size_t id, const void* data )
    {
        iterator_type it( list.find( id ) );

        if ( it != list.end() )
            ( this->*( it->second ) )( data );
    }

private:
    std::map< std::size_t, memfun_ptr > list;
};

struct derived : base
{
    static derived* create()
    {
        static int instances = 0;

        assert( !( instances++ ) && "zu viele instanzen" );

        static derived inst;
        return &inst;
    }

    void test( const void* data )
    {
        std::cout << "calling derived::test()\n";
    }

    void foo( const void* data )
    {
        std::cout << "calling derived::foo()\n";
    }
};

int main()
{
    base* a = base::create();

    derived* c = derived::create();
}