Why super() can be used in Constructor only?

programming flash
1

I just wondering why super() can be used in Constructor only but not in other function?
for example:

package
{[INDENT] public class mySubClass extends myClass
{[INDENT] public function mySubClass()
{[INDENT]super(); // ok, you can use super anywhere in this constructor
[/INDENT]}

override public function myFunction()
{[INDENT]super(); // NO WAY MAN!
// extending code here
[/INDENT]}
[/INDENT][/INDENT][INDENT] }
[/INDENT]}

What I want is to extend a function without rewriting the old one. Anybody has an idea?

2

mmmm, I think you can still call the function w/ something like “parent::myFunction();” or since you are extending myClass, “myClass::myFunction”

don’t quote me on that, I may have just stolen syntax from PHP :stuck_out_tongue:

3

A super statement may only be used inside a constructor.

Reason why might be because you are extending something, you need to instantiate (if ever) the extended class when you are instantiating your subclass.

4

I found your answer with this adobe example: (little disclaimer - this is in the adobe flex area of livedocs, and I didn’t test before posting :stuck_out_tongue: )
http://livedocs.adobe.com/flex/201/html/wwhelp/wwhimpl/common/html/wwhelp.htm?context=LiveDocs_Book_Parts&file=10_Lists_of_data_166_6.html

It appears that a super does not have to be only within the constructor (at least, in the form of a method).

Check out where it says “TypedArray overridden methods”

the function overrides the “push” method of an array and still calls “push” via:
ActionScript Code:
[LEFT][COLOR=#0000ff]super[/COLOR].[COLOR=#0000ff]push[/COLOR].[COLOR=#0000ff]apply[/COLOR][COLOR=#000000]([/COLOR][COLOR=#0000ff]this[/COLOR], args[COLOR=#000000])[/COLOR]
[/LEFT]

5

AS3 super() statement;

http://livedocs.adobe.com/specs/actionscript/3/wwhelp/wwhimpl/common/html/wwhelp.htm?context=LiveDocs_Parts&file=as3_specification152.html

6

this works, just tested it:


package {
	
	public class myparent {
		
		public function myparent() {
			trace('parent constructor');
		}
		
		public function parentSpeak():void {
			trace('parent speaks');
		}
	}
}



package {
	
	import myparent;
	
	public class mychild extends myparent {
		
		public function mychild() {
			trace('child constructor');
		}
		
		public function childSpeak():void {
			trace('child speaks');
			super.parentSpeak();
		}
	}
}

Implementation code:


import mychild;

var it:mychild = new mychild();

it.childSpeak();

output:


parent constructor
child constructor
child speaks
parent speaks
7

flex uses as3, so it’s methods / structure is (mostly) the same
super() != super.method

My suggestion to the OP is to use super.myFunction(); which should go to the overridden function in the parent class and perform that code

8

Sorry fido, didn’t really read your posts properly. Thought you were saying you could use super() outside cnstrctr. Your examples work fine :wink:

9 
package {
   public class mySubClass extends myClass {
      public function mySubClass() {
         doSomething();
         super();
      }
      override public function set width(value:Number):void {
         super.width=value<100?100:value;
      }
      override public function myFunction(param:*):void {
         doSomething();
         super.myFunction(param);
         doSomethingElse();
      }
   }
}
10

aha, so the answer is super.myFunction(); I really stupid, why couldn’t I find this soon. Thank you guys! :party: