Logic Operator ||= in AS3

Bruno Sales — Fri, 28 Aug 2009 18:33:59 +0000

Well, few people knows about the logic operator "||=". I'll try to explain a little more about it.

In the adobe documentation, this operator is described like: "Assigns expression1 the value of expression1 || expression2". Just to remember, the sintaxe to logic operator is "expression1 operator expression2".

I'll show some examples of how it works.

Exemple1:

PLAIN TEXT

ACTIONSCRIPT:

var array:Array; // Variable arr is null.
array ||= ["Bruno Sales"]; // In case array is null, assign the value ["Bruno Sales"]
trace(array.toString()); // Result: New value assigned, trace prints "Bruno Sales"

Exemple2:

PLAIN TEXT

ACTIONSCRIPT:

var array:Array = ["DClick"]; // Variable arr has the value ["DClick"].
array ||= ["Bruno Sales"]; // In case array is null, assign the value ["Bruno Sales"]
trace(array.toString()); // Result: No value assigned, trace prints "DClick"

Soon, looking the difference of this 2 exemples, we conclued that the logic operator "||=" makes the same thing of the code below, but in a better way.

PLAIN TEXT

ACTIONSCRIPT:

var array:Array = ["DClick"];
if (array == null)
{
array = ["Bruno Sales"];
}

I hope you all liked it.

Variable Scope in ActionScrip 3

Bruno Sales — Sun, 26 Jul 2009 00:44:26 +0000

Twitter!

Do you know what happens in the follow code?

PLAIN TEXT

ACTIONSCRIPT:

var test:Boolean = false;
if(test)
{
var name:String;
}
else
{
name = "Bruno Sales";
}
trace("Name: " + name);

Compile error? Runtime Error? Nothing. The trace result is "Name: Bruno Sales". The variable was created even if the code inside the IF was never executed.
Thats happens because ActionScript has just 2 types of scope: Global and Local; remembering that Local is everything inside a function.

However, I suggest never using something like this in your development process. Your code logic will be very confusing and will cause problem to maintenance and debug.

DClick Team Weblog [en] » Programação

Logic Operator ||= in AS3

Variable Scope in ActionScrip 3