What is the difference between a literal value and a constructor?

[Guest]

1)what is the difference between a literal value and a constructor?

example:

var someArray:Array = new Array(1,2,3); // Array constructor

var someArray:Array = [1, 2, 3]; // literal value

2)what is the "new" operator, and it serves?

3)what is a constructor?

I'm reading AS3 Fundamentals

, and so far I have failed to understand that.

Learning ActionScript 3 | Adobe Developer Connection

Thnks ALL!!!

[sinious · Accepted solution]

Nothing more than shorthand ECMAScript. You can do this in JavaScript as well. Both objects are instances of the Array class.

When you generate a large matrix you will appreciate the shorthand approach. It's much more friendly to read. For example:

var tileMapA:Array = [ [1, 1, 1, 1, 1],
                       [2, 2, 2, 2, 2],
                       [3, 3, 3, 3, 3] ];

VS:

var tileMapB:Array = new Array( new Array(1, 1, 1, 1, 1),
                                new Array(2, 2, 2, 2, 2),
                                new Array(3, 3, 3, 3, 3) );

Not a huge difference immediately but expand these into much more complex nested Array structures and you'll see the difference clearly. Same thing goes for new Object() or just { }.

[Amy Blankenship]

I think it mainly comes down to speed. However, which version is fastest probably varies by Flash Player version, which you usually can't control.

[sinious]

And to directly address your question on the constructor, in class based AS3 the same constructor is used in both instances.

e.g.

var a:Array = [1];
var b:Array = new Array(1);

trace('a:' + a.constructor + ', b:' + b.constructor + ', same:' + (a.constructor === b.constructor));

Traces:

a:[class Array], b:[class Array], same:true

[Guest]

thanks for replying! no remains of any clear, but very good answers!

[sinious]

You should feel free to use either form. You'll find this quite a bit in programming. Many ways to do essentially the same thing!

You're welcome and good luck!