[mtasc] Re: [OT] Dynamic variables?

[Timo Stamm]

Firdosh Tangri wrote:
> dynamic classes are usefull when you want to add properties at run time for 
> example
> 
> var person:Object=new Object();
> person.name="John";
> person.age=23;


You could do the very same with a class:

class Person {
	public name : String;
	public age : Number;
}

...

var p : Person = new Person();
p.name = "John";
p.age=23;



And have the compiler check the type at compile time...

The disadvantage: You need you an extra class file (I guess AS doesn't 
know inner classes?)


I think it is mostly a matter of personal preference whether you like 
classes and compile-time checking or more freedom (and more potential 
sources for runtime errors).

I like being able to create an object with as few keystrokes (and no 
extra class) like this:

var p = { name : "John", age : 23 }


So this is basically a question of programming style. But there are 
other reasons, see below:


> On 9/6/05, tcornel <tcornel at gmail.com> wrote:
> 
>>Actually, i was wondering what's the deal with the dynamic classes,
>>and why not one who wants to add a method to a class would not simply
>>extend that class (inheritance).


Take a look at this extension of the built-in Array:


Array.prototype.unique = function () {
          o = [];
          for (i in this) {
                  d = 0;
                  for (j in o) {
                          if (o[j] == this[i]) {
                                  d++;
                          }
                  }
                  if (d < 1) o.push(this[i]);
          }
          return o;
}
ASSetPropFlags(Array.prototype , null, 1);



usage:

[1, 2, 2].unique()


This would not be possible using a subclass.


It is similar with attachMovie, loadMovie, createEmptyMovieClip. You can 
use registerClass with attachMovie, but in my experience it's best to 
use a Delegator (the design pattern as defined by the GOF, not 
mx.utils.Delegate) to wrap the MovieClip class, and derive your subclass 
from that (that's entirely my opinion, though).


Timo


>>
>>regards
>>Cornel
>>
>>On 9/6/05, Till Schneidereit <tschneidereit at gmail.com> wrote:
>>
>>>One way to get around this problem is to use (static) subclasses of the 
>>
>>built in dynamic classes whereever possible. That way, you get all members 
>>of the superclass without having to deal with its dynamic nature ...
>>
>>>>This is very frustrating, i'm used to c++ and trying to learn
>>>>actionscript. So, i was wondering,are there some methods to avoid this
>>>>kind of errors? I really hate dynamic classes...
>>>
>>>cheers,
>>>till
>>>--
>>>MTASC : no more coffee break while compiling
>>>
>>
>>--
>>MTASC : no more coffee break while compiling
>>
> 
> 
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> MTASC : no more coffee break while compiling