import std;

​

interface Renderer

{

}

​

struct VTable

{

   void function(Chip, Renderer) draw;

}

​

void drawHovered(Chip c, Renderer renderer)

{

    writeln("hovered ", c.state);

}

void drawInitial(Chip c, Renderer renderer)

{

    writeln("initial ", c.state);

}

VTable Hovered = VTable(&drawHovered);

VTable Initial = VTable(&drawInitial);

​

void main()

{

    Renderer renderer;

​

    auto chip = new Chip();

​

    // Test Draw

    // 1. Init

    chip.draw( renderer );

    // 2. Hovered

    chip.to(Hovered);

    chip.draw( renderer );

​

    // 3. Init

    chip.to(Initial);

    chip.draw( renderer );

    // 4. Hovered

    chip.to(Hovered);

    chip.draw( renderer );

}

​

class Chip

{

    int state = 7;

    VTable vtable;

    this()

    {

        vtable = Initial;

    }

    void to(VTable newVtable)

    {

        vtable = newVtable;

    }

    void draw( Renderer renderer )

    {

        vtable.draw(this, renderer);

    }

}

​

​