Re: [flexcoders] When to use constructor vs init?

Tue, 27 Sep 2005 14:48:15 -0700

Thank you for the explanation, that does help

-Rick

On 9/26/05, JesterXL <[EMAIL PROTECTED]> wrote:
Depends on what you extend, and what you are creating.
 
Extending nothing (implicit inheritance from Object), no need to have default properties?
 
Then nothing.
 
Extending nothing, but need to have customizable properties?
 
Pass them into the constructor.  Some would argue you should utilize an init instead since it's easy to re-initialize a class instance with new data vs. recreating the whole thing.  Example:
 
a = new Cow();
a.init(name, dateOfBirth);
a.init(anotherName, anotherDate);
 
vs bad way:
 
a = new Cow(name, dateOfBirth);
a = new Cow(anotherName, anotherDate):
 
Most Model classes have public properties so you don't even need a constructor or init function since you can just set the properties.  Others have public methods accomplishing the same thing.
 
The third facet is if you are extening something that automatically calls your constructor or some other sub function.
 
For example, extending mx.core.UIObject, UIComponent, or View have a bunch of built-in functions that run automatically.  You don't need to even define a constructor, although it's nice as a best practice.  For example, if you extend UIObject, you're init function is called for you automatically, and at that point, if you passed in an initialization object, those properties are already set.
 
So bottom line, I rarely use constructors.  Most of the teaching programming books I've seen show those as examples, but I don't ever use them in the real-world, and if I do, it's only for intrinsic model classes (Array, Date, etc.).  None of my View classes ever take parameters because currently, Flash Player requires factory methods to create things vs. a = new MovieClip().
 
Hope that helps.
 
 
----- Original Message -----
Sent: Monday, September 26, 2005 1:34 PM
Subject: [flexcoders] When to use constructor vs init?

When making a custom class, should you ever put anything in the constructor? 

class foo {

function foo(){
  // do stuff here like add event listeners?
}

function init(){
   super.init()
   // do stuff here like add event listeners?
}

}


Also should super.init() be first or last inside of init()?


I've seen examples using either, and sometimes both


Thanks!


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