const

const HALF_PI:Number = Math.PI / 2;
const RADS:Number = Math.PI / 180;

trace(HALF_PI);
// convert degrees to radians
trace(180 * RADS);

When I have constant values I often forget to go ahead and make use of the const keyword. I used to do this a good deal when AS3 first came out…. not sure why I stopped doing it. Anyway, hopefully this post will help remind me to use them…

A very common use for them is of course defining event types:

// inside a class
public static const RENDER_COMPLETE:String = "renderComplete";