Re: Question on shapes

[JG via Digitalmars-d-learn]

On Tuesday, 17 May 2022 at 00:10:55 UTC, Alain De Vos wrote:
Let's say a shape is ,a circle with a radius ,or a square with 
a rectangular size.
I want to pass shapes to functions, eg to draw them on the 
screen,
draw(myshape) or myshape.draw();
But how do i implement best shapes ?

You could also do something like:
```d
import std;

struct Circle {
    double radius;
    void draw() {
        writeln(format!"Draw a circle of radius %s"(radius));
    }
}

struct Rectangle {
    double width;
    double height;
     void draw() {
        writeln(format!"Draw a rectangle of width %s and height 
%s."(width,height));
    }
}

alias Shape = SumType!(Circle,Rectangle);


void main() {
  Shape[] shapes = [Shape(Rectangle(2.0,3.)),Shape(Circle(3.0))];

  foreach(shape; shapes) { shape.match!(x=>x.draw); }
}
```

or

```d
import std;

struct Circle {
    double radius;
}

struct Rectangle {
    double width;
    double height;
}

alias Shape = SumType!(Circle,Rectangle);

struct Drawer {
    int drawerState;
    void drawShape(Shape shape) {
        shape.match!(x=>drawShape(x));
    }
    void drawShape(Circle circle) {
        writeln(format!"Draw a circle of radius 
%s"(circle.radius));
    }
    void drawShape(Rectangle rectangle) {
        writeln(format!"Draw a rectangle of width %s and height 
%s."(rectangle.width,rectangle.height));
    }
}

void main() {
  Shape[] shapes = [Shape(Rectangle(2.0,3.)),Shape(Circle(3.0))];
  Drawer d;
  foreach(shape; shapes) { d.drawShape(shape); }
}
```