A Quick Assignment Operation

In AS3, like any programming language, there are lots of little tricks you pick up that eventually become part of your own coding style. One such for me was shown to me by Guy Wyatt (Guy, I wanted to make your name a link, but I’m not sure where to send it):

var foo:String = someValueThatMayBeNull || "Backup String";

In this assignment, the value of “someValueThatMayBeNull” may, in fact, be null, an empty string, or something else that evaluates to false. If that’s the case, our variable “foo” will get the value “Backup String” instead. It’s just one of the neat things about order of operations and assignment.

I’ve used this for a long time now, and it’s pretty awesome, especially for dealing with flashvars, but the other day I ran into an assignment operator that was even cooler. I know, hard to believe, right?

This came up in a “getter” method, but I could see it being equally useful in singleton instantiation. Check it out:

return _privateVar ||= new InstanceOfPrivateVar();

The “||=” operator is really cool. It works just like the previous example, but rather than just returning our new instance, it also assigns it to _privateVar on the way. So next time we call that getter, _privateVar will already be assigned. Woo!

Ok… so, there’s got to be someone else out there who is as excited as me about this. Share the love.