import std.stdio;

struct Rect {
    int width, height;

    // This `area` method is defined for the `Rect` struct.
    int area() {
        return width * height;
    }

    // Methods can be defined for either reference or value types.
    // Here's an example of a value type method.
    int perim() {
        return 2*width + 2*height;
    }
}

void main() {
    Rect r = Rect(10, 5);

    // Here we call the 2 methods defined for our struct.
    writeln("area: ", r.area());
    writeln("perim:", r.perim());

    // D automatically handles conversion between values
    // and references for method calls. You may want to use
    // a reference type to avoid copying on method calls or 
    // to allow the method to mutate the receiving struct.
    Rect* rp = &r;
    writeln("area: ", rp.area());
    writeln("perim:", rp.perim());
}