Calling a handler?

[Nicollini webforumsuser@macromedia.com]

I'm new to oop so please bare with me, I hope you can answer my question.

I have a parent script which has an ancestor. I basically want to call a handler from the parent scirpt to where the handler sits (in the ancestor script).

Or to put another way I need to send a message from the parent script to the ancestor script.

I've just tryed to call the handler as normal as I thought the handlers within the ancestor were accessible to the object. However I get an error that the handler is not defined.

Can anyone help???

Thanks.

Nick

[SafariTECH]

the easiest way is to make sure the handlers that can be called from any other location are made in their own members as "Movie Scripts", not behaviours.

Then you can call them just by stating the handler name.

You can also use Handlers to RETURN data back to a variable in a similar fashion.



============================
Glen Palmer
SafariTECH
Cold Fusion Specialist
[url]www.safaritech.com[/url]
============================

[Luke]

> I've just tryed to call the handler as normal as I thought the handlers
within the ancestor were accessible to the object. However I get an error
that the handler is not defined.

There are two ways of 'calling handlers' in Director:

(1) The 'functional' way where you just call the handler like this

handlerName()

with no reference to the object with the handler. In this case, Director
first looks in the current script (whether it is a movie script, parent
script or behaviour) to see if there is a handler with that name. If not, it
then goes and looks in all the movie scripts until it finds that handler. If
it cannot, if generates a "Handler not defined" error.

(2) The second way is more 'object-orientated'. In this case, you 'call a
handler' by "sending a message to an object". To do this, you must specify
which object has the handler. There a numerous ways of doing this

object.handlerName()
handlerName(object)
call(#handlerName, object)
sendSprite(1, #HandlerName)
etc

In each of these examples, you are specifying which object has the
handler.When Director evokes the handler, it always passes a reference to
the object that was sent the message as the first parameter. By convention,
this first parameter is called "me" (or "this" or whatever you want).

What happens when an object has an ancestor is that any messages sent to the
object (which that object cannot respond to) are passed 'up the inheritence
chain' to the object's ancestor. When this occurs, the descendant object
(the object that originally received the message) 'becomes' the ancestor
object for the purposes of responding to the message (and the "me" parameter
in the ancestor will point to the decendant object when it handles the
message sent to the descendant).

So, to call the handler (or "method", as they are called in OOP terminology)
of the ancestor from the descendant, you can do any of the following:

me.HandlerName()
-- if the current object ("me") doesn't have a handler called "handlerName"
then object will use the ancestor's method (the "me" in the ancestor's
method will point to the descendant)

ancestor.HandlerName()
-- in this case, you are specifying the ancestor object as the recipient of
the message (the "me" in the ancestors method will point to the ancestor)

callAncestor(#HandlerName, ancestorObject)
-- use this syntax when the ancestor and the descendant have a method with
the same name but you do want the descdant to over-ride the ancestor's
method but still want call the ancestor's method as if it were inherited
like example 1)

HTH

Luke

[Stephen Whipp]

Yeah but this defeats the purpose of programming in an object oriented
style. The Advantage of using parentScripts/behaviors is that you can a,
share common functions/data between similar entities b) you can create many
objects with the same code but having different data (wthout having to
handle large list of their data manually) an c) you can reuse handler names
because they are handled by context thereofre making the code easier to
follow becuase you dont need very long or meaningless identifiers.

SafariTECH <contact@safaritech.com> wrote in message
news:bj7gbq$fcp$1@forums.macromedia.com...

> the easiest way is to make sure the handlers that can be called from any

other location are made in their own members as "Movie Scripts", not
behaviours.

>
> Then you can call them just by stating the handler name.
>
> You can also use Handlers to RETURN data back to a variable in a similar

fashion.

>
>
>
> ============================
> Glen Palmer
> SafariTECH
> Cold Fusion Specialist
> [url]www.safaritech.com[/url]
> ============================