From: Jeff Wood <jeff.darklight@...>
Date: 2005-10-08T00:27:27+09:00
Subject: Re: Event Handling

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You could always make your adapter collection a hash instead of an array,
then you would have a name to be able to replace/delete by.
 j.

 On 10/7/05, Robert Klemme <bob.news@gmx.net> wrote:
>
> James Edward Gray II wrote:
> > On Oct 7, 2005, at 8:46 AM, iamscottwalter@gmail.com wrote:
> >
> >> Hi,
> >
> > Hello and welcome.
> >
> >> I am coming from the Java world and was wondering if there ins
> >> anything
> >> in Ruby similar to Java's event processing? For example I have a
> >> particular Object that can fire off an event to all objects that
> >> listen
> >> for that event. A more real world example would be that I have a
> >> delete() method that was called and I want to let all interested
> >> parties know that the delete() method was called.
> >>
> >> In the Java space I would setup an event listener. When the delete()
> >> method would be called I wouold send an event to all my registered
> >> listeners.
> >
> > I think you are looking for observer, in Ruby's standard library:
> >
> > http://www.ruby-doc.org/stdlib/libdoc/observer/rdoc/index.html
>
> This started in interesting thought with me: a block would come in handy
> as listener as well. In fact "adapter" might be a better name and what we
> get then seems to be quite similar to the C# approach.
>
> class SomeObserver
> def register(observable)
> observable.add_observer do |*a|
> puts "changed" if DEBUG
> @model_change =3D true
> # ...
> end
> end
> end
>
> Disadvantages I see so far
>
> - removal of adapters is impossible
>
> - a lot unnecessary adapter objects might be created
>
> Alternative approach:
>
> class SomeObserver
> def register(observable)
> observable.add_observer adapter(observable) do |*a|
> puts "changed" if DEBUG
> @model_change =3D true
> # ...
> end
> end
>
> def adapter(obj,&b)
> @adapters[obj] ||=3D ( b; class <<b; alias :update :call; end; b )
> end
> end
>
> Sorry, just loud thinking...
>
> Kind regards
>
> robert
>
>
>


--
"http://ruby-lang.org -- do you ruby?"

Jeff Wood

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