From: ara.t.howard@...
Date: 2006-02-02T01:01:36+09:00
Subject: Re: callbacks, events, notification in general

On Thu, 2 Feb 2006, Damphyr wrote:

> OK, bare with me, this is brainstorming of a sorts:
> I want to have some kind of event notification from my classes.
> Typically what I would do would be to pass a logger object and let the
> class log by itself, but I'm not really satisfied with this solution in
> most cases.
>
> What I would prefer was define a callback method and give this to the
> object. Then I could do whatever I want with it and not only use logs.
> Mostly I want to have progress reports.
>
> something like
>
> class A
>  def set_callback notify
>    @notify=notify
>  end
>  def something
>    puts "something"
>    send(@notify) if @notify
>  end
> end
>
> def coocoo
> 	puts "hey"
> end
> a=A.new
> a.something
> a.set_callback(:coocoo)
> a.something
>
> Now this does exactly what I want and can be wrapped up in a module to
> be included for general use.
> Question: Is there a "better" solution? What are my alternatives?
> Cheers,
> V.-

     harp:~ > cat a.rb
     require "observer"

     class A
       include Observable
       def something
         changed and notify_observers 42
       end
     end

     class B
       def update arg
         p arg
       end
     end

     a = A::new
     b = B::new

     a.add_observer b
     a.something


     harp:~ > ruby a.rb
     42

always a good start to read about the stdlibs!  ;-)

cheers.

-a

-- 
happiness is not something ready-made.  it comes from your own actions.
- h.h. the 14th dali lama