On 23.09.23 05:11, Vitaliy Fadeev wrote:
On Friday, 22 September 2023 at 19:50:17 UTC, Christian Köstlin wrote:
another option could be to model your own VTable in a struct like this:
https://run.dlang.io/is/3LTjP5
Kind regards,
Christian
Thank, Christian !
True nice tasty solution with ```VTable```!
And further... the project is growing.
```
void Draw()
{
DrawBG();
DrawFG();
}
```
And we want use ```DrawBG()``` code from ```initial``` in other states,
like ```Selected```.
How to use some functions from ```initial``` via ```VTable``` ?
I see solution in ```classes``` and methods with ```override``` keyword.
```VTable``` does the same thing as ```__vptr``` ?
VTable is your structure .. it does exactly what you want it to do.
__vptr is the internal implementation of virtual methods in the dlang
object model.
Line 20 and 21 in my example initialize the two `VTable`s Initial and
Hovered. You can change VTable to contain two function pointers and
initialize those as you like for the instances of the VTable structs.
e.g.
```d
struct DrawVTable
{
void function(Chip, Renderer) background;
void function(Chip, Renderer) foreground;
}
// define functions to draw the different fore and backgrounds
...
...
VTable initial = VTable(&drawInitialBackground, &drawInitialForeground);
VTable hovered = VTable(&drawHoveredBackground, &drawHoveredForeground);
VTable selected = VTable(&drawInitialBackground, &drawHoveredForegtround);
```
Kind regards,
Christian
