Sorry I didn't explain well. It really is a dead point as it can't be done.
I was just wonder if anyone knew the design reason. But anyway, here is
what I wanted to do.
ClassA
public var level : int = 0;
ClassB extends ClassA
override function get level() : int
{
return
determineLevelBasedOnUserPermissions(super.level);
}
private function
determineLevelBasedOnUserPermissions(level:int) : int
{
// Do crazy stuff here to determine new level based on user
permissions
// Audit if calculated level is different that level
return calculatedLevel;
}
The extended class takes user permissions into account for a specific part
of the app. Unfortunately the super class has level as a public var. Been
that way for a long time. With this new feature spec we need to modify in a
single place in the app based on user permission.
Already had the super class change to get/set so we are past it. Better
solution would have been remove all access to the property and change to
real function to get them and let the function decide when user permission
is in order, but that was more refactoring than we are prepared to do right
now (although easy refactoring).
I was just wondering if anyone knew why. I could see this as a problem if a
person was to download a non open source swc and the builders of that swc
didn't put in the boilerplate get/set and instead just left the var public.
Bottom line is that I'll now start putting in that dreaded boilerplate
get/set code in my classes that will become part of a library.
Dale
From: [email protected] [mailto:[email protected]] On Behalf Of Darin Kohles
Sent: Tuesday, December 07, 2010 8:10 PM
To: [email protected]
Subject: Re: [AFFUG Discuss] Needs override, doesn't allow override
I guess perhaps I am missing then what you were trying to do? There is no
reason to even mention a super class public variable in a subclass
declaration, it is included by definition.
Class A{
public var foo:*;
}
Class B extends A{
}
instanceOfA.foo = bar;
instanceOfB.foo = bar;
(instanceOfB as A).foo = bar;
(instanceOfA as B).foo = bar;
All 4 of the above statements are valid as you can cast up and down the
class hierarchy for any public variables. Super classes all pass through
their public variables to subclasses, so there is no reason to re-declare or
override.
so:
Class C extends B{
}
instanceOfC.foo = bar; // the inheritance chain passes through all public
variables and functions.
On Tue, Dec 7, 2010 at 5:30 PM, Dale Bronk <[email protected]> wrote:
Thanks. I'm actually not setting to an explicit value, just left that code
out as it is not important to the question. Do you know the design reason
for not being able to override the variable with implicit (although explicit
after compilation) getter/setter?
One of the things I love about ActionScript is that we are not forced to
create boiler plate code for getter/setter for each variable. I come from
the Java world and we need to do that. I find great power in just making
the property public. Then any other class that needs to get or set can
simply do something like myObj.foo = bar. If later myObj decides that the
setter should do something else, simply tweak the code and add the setter.
The other classes code does not need to change, it still just does myObj.foo
= bar. In Java, this is not the case, you'd have to do myObj.setFoo(bar).
I love the fact that we don't have to litter our code with boilerplate
getter/setter and only implement if we need more processing during a get or
set.
With the way it works with not being able to override really removes this
ability. I know that we have code generators for creating getter/setters
and we can collapse the code in the IDE, but that still has a bunch of dumb
code that needs to be there. So if you know the design reason, I'd love to
know what it is.
Thanks,
Dale
From: [email protected] [mailto:[email protected]] On Behalf Of Darin Kohles
Sent: Tuesday, December 07, 2010 4:20 PM
To: [email protected]
Subject: Re: [AFFUG Discuss] Needs override, doesn't allow override
Public properties have implicit getter/setter behavior, but as you found you
can not override an implicit function with an explicit override (yes, once
compiled their will be an actual explicit function if you look at the
source, but this doesn't help you during compilation).
If Class A is always used as a super class, have your colleague change it
from public to protected. If however, you really want to add custom
code/functionality for the retrieval of the variable that is different than
what is supplied by the underlying public property (in your example it looks
like you are trying to force it to return a set value regardless of what the
actual value is).
I'd suggest playing with BindingUtils (assuming the public property
iAmPublic is [Bindable]):
var cw:ChangeWatcher = BindingUtils.bindSetter( overrideSet, this,
iAmPublic);
private function overrideSet( value:int ):void
{
iAmPublic = 9;
}
This guarantees that if the property is set, it is set to the value you
want, but does not guarantee that the property has a value (or in this case
a specific value. You can ensure the property is set by explicitly assigning
a vale (then overridden to your desired value) during initialization.
On Tue, Dec 7, 2010 at 2:51 PM, Dale Bronk <[email protected]> wrote:
I'm sure there is a reason for this, but I don't know it and can't seem to
find it googling.
I have:
ClassA
public var iAmPublic : int = 0;
ClassB extends ClassA
public function get iAmPublic() : int { return 9; }
- or -
override public function get iAmPublic() : int { return 9; }
Both compile error out. Either with I must override the function or invalid
override.
If I change ClassA to have public function get/set .... it will work fine.
I realize that behind the scenes a get/set must be created for me, but it
seems to me the compiler should be smart enough to handle this. The big
problem is that I'm dealing with a swc that has the property as a public var
so I can't override it.
Anyone have any ideas? I can go to the person and have them change it to do
getter/setter, but doesn't this seem like something that should just work?
Thanks,
Dale
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