Casting to union type?

[cc via Digitalmars-d-learn]

Ahh, thanks.  Looks like encapsulating the union in a struct with 
alias this gets the job done, and removes the need for overloads. 
  Neat.

struct vec2 {
	union {
		struct {
			float x = 0.0f;
			float y = 0.0f;
		}
		float[2] v;
	}

	this(float x, float y) {
		this.x = x;
		this.y = y;
	}
	this(float[v.length] f) {
		v[0..length] = f[0..length];
	}
	alias v this;
}