Comments on: ActionScript 3 Loops

By: jackson

jackson — Sat, 19 Sep 2009 17:24:42 +0000

Oh, it’s definitely the most flexible loop. It also involves the most typing, both on the keyboard and as far as data types. Almost all of my C-style for loops involve an explicit cast where I cache the current value. You’re right about the mixed-type problem though. In this case you’re forced into using the is operator like this:

var len:int = someArray.length;
for (var i:int = 0; i < len; ++i)
{
  var cur:* = someArray[i];
  if (cur is Point)
  {
    var p:Point = cur as Point;
    // do stuff with the point here...
  }
  else if (cur is Matrix)
  {
    var m:Matrix = cur as Matrix;
    // do stuff with the matrix here...
  }
}

It’s worth noting that you don’t have an option here: C-style loops give you the flexibility you need because there’s no super class of Point and Matrix that’s useful (Object doesn’t count).

Thanks for the comment!

By: Alan

Alan — Sat, 19 Sep 2009 16:17:04 +0000

In Actionscript, when using the C-style loop, casting the accessed array item will allow for run-time errors and code completion.

If the items in the array are of mixed type, this would be less helpful – unless you are able to cast to a super class.

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Tweets that mention ActionScript 3 Loops « JacksonDunstan.com -- Topsy.com — Wed, 16 Sep 2009 18:20:11 +0000

[...] This post was mentioned on Twitter by Franky. Franky said: for each (var item in list) seems to "cache" list, probably on the stack. http://bit.ly/11OSLu (via @robpenner) [...]