Hi stranger , :)
I dont think I quite understand what you need, however i will try anyway.
[quote] "How do you get a super-class instance to call an over-riding
method in a sub-class"
Inheritance assumes that you use a 'general' base class and a
'specialized' subclass. To make sure I understand you right : You
need to call a method on a child class from inside the Parent class,
right ? Does it matter from where you call the method ? As long as
you have a reference to the subclass instance - call the method directly.
class MySuperClass extends Object {
.. important general code here ....
}
class ChildClass extends MySuperClass {
... important specialized code here ....
}
var msc:Class = new MySuperClass();
var childRef:ChildClass = msc.getChildClassFromList() as ChildClass;
( I assume the class was stored inside an Array(List) )
childRef.doDesiredAction( 'execute some really important childClass
code' ); // there you go :)
[quote] "Furthermore, any input values not caught by the parsers of
the sub-classes need to get passed back up to the super-class."
Calling a method of the Superclass is easy. Just use 'super'.
var msc:Class = new MySuperClass();
var childRef:ChildClass = msc.getChildClassFromList() as ChildClass;
( I assume the class was stored inside an Array(List) )
class MySuperClass extends Object {
.. important general code here ....
public function doDesiredAction( arg:String){
super.doGeneralDataProcessing( arg );
}
}
class ChildClass extends MySuperClass {
... important specialized code here ....
public function doDesiredAction( arg:String){
super.doGeneralDataProcessing( arg );
}
}
childRef.doDesiredAction( 'calls the super class' ); // there you go :)
[quote] "Does this make sense?"
No offense , but no !!! First as a general rule of thumb: 'Favor
Composition over Inheritance' [Sierra|Bates] - Inheritance ties you
down. Say you implement the system as you described
and in 3 months you need to change the BaseClass - suddenly all your
subclasses, needing to call the base class for processing, must be
changed since they all depend on your
base class -> Strategy Pattern is recommended over inheritance ( but
thats just my opinion )
Command Pattern to execute the different Parser Classes.
It seems to me that your classes have high coupling / low Cohesion -
meaning that you use several classes to get one job done , it may
seem like a good idea at first ,
using the specialized class A, the base class B, another specialized
class C and so on to work together and parse the desired data.
However it is advised that each class takes care of One
Responsibility. I dont want to be pretentious, so if you already know
all that , please forgive :)
So I assume you have written one parser for each special file format
- a .xml parser , a .txt parser, a loadVars parser and so on.
They all extend MySuperParser. So why splitting responsibility of
parsing data across base and child classes ?
Has the BaseClass features / responsibilities that all subclasses
need ? if so - fine, just call the base class methods from inside your
specialized subClass Parser BEFORE you do the specialized processing like so :
public function mySubClassSpecializedParsingMethod( specialParam:* ) :void {
super.BaseClassPrepFirst( specialParam );
var preppedData:* = super.getPreppedData(); // I havent
really tried this line :) see wether it works
this.doSpecializedPrepping( preppedData );
}
If you want to freshen up on Composition over Inheritance - This Book
is my all time favoured Design Pattern and Bets Practice Programming
Book !!!!!!
HEAD FIRST - DESIGN PATTERNS ( Elisabeth Freeman & Eric Freeman ||
Kathy Sierra || Bert Bates )
This was the best Book about Design Pattern - actually generally
about good Programming.
I hope I was able to help you a bit - did I get it right ? I hope :)
Best of luck
Amir
P.S.
Lingo is NOT OOP -> dont get me wrong ! lingo rocks!!! but its
nothing like ActionScript or Java -> Even the Javascript DOM for
Lingo is strange to say the least :)
But again - lingo rocks!!
Am 11:32 PM 6/29/2007 schrieben Sie:
How do you get a super-class instance to call an over-riding method
in a sub-class? I'm using AS2.
I'm parsing data into an object. The parser method is generalized,
so it should be in the super-class, I think... But there are
exceptions in the sub-classes. The call to start loading the data
begins in the super-class, but some of the sub-classes might have
there own over-riding parser methods. Furthermore, any input values
not caught by the parsers of the sub-classes need to get passed back
up to the super-class.
Does this make sense? I did this kind of thing all the time with
lingo, but since I've been reading Moock I'm trying to write better
OOP. This has got to be a pretty common thing to run across.
Thanks!
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