From: Jack Dempsey <dempsejn@...>
Date: 2002-01-16T01:44:46+09:00
Subject: RE: benefits of callbacks

Ok...the idea made sense before, but I can see how this would really save
some time in certain situations.

Thanks!
Jack

> -----Original Message-----
> From: Sean Middleditch [mailto:elanthis@awesomeplay.com]
> Sent: Tuesday, January 15, 2002 11:43 AM
> To: ruby-talk ML
> Subject: RE: benefits of callbacks
>
>
> Signals.  You can register a function (or an object, in Ruby) to listen
> to a particular function in another object.  Then, when said signal is
> generated, the callback is activated.
>
> The place this is most commonly used is a GUI.  For example, you can
> register an object to be called when a user signal is generated (user
> clicked on OK button).
>
> Without callbacks, you'd have to, for ever GUI object, make a child
> object with some form of "activate" method or something, which would be
> more complex (depending on the exact situation).  And then, on top of
> that, only the child object could respond - if you need multiple
> sections of code to be updated when a signal is generated, it wouldn't
> be possible without callbacks (or some really really ugly code).
>
> Another way to look at callbacks is the way Ruby allows you to
> dynamically change a method in an object.  This is, really, just another
> form of callbacks.  Setting the method is analogous to registering a
> callback; when the object invokes the method, it's just like calling a
> callback.  Of course, setting a method of an object is limited in that
> you can only have *one* callback registered for a particular purpose at
> a time...
>
> On Tue, 2002-01-15 at 11:31, Jack Dempsey wrote:
> > Ok, but being in Ruby (which most certainly is OO =P), why are
> callbacks so
> > useful?
> >
> > Thanks!
> > Jack
> >
> > > -----Original Message-----
> > > From: Ralph Mason [mailto:ralph.mason@telogis.com]
> > > Sent: Tuesday, January 15, 2002 2:47 AM
> > > To: ruby-talk ML
> > > Subject: Re: benefits of callbacks
> > >
> > >
> > > A callback gives the power of a virtual or late binding function
> > > to a non OO
> > > language.
> > >
> > > Will that do?
> > >
> > > Ralph
> > >
> > > ----- Original Message -----
> > > From: "Jack Dempsey" <dempsejn@georgetown.edu>
> > > To: "ruby-talk ML" <ruby-talk@ruby-lang.org>
> > > Sent: Tuesday, January 15, 2002 8:10 PM
> > > Subject: benefits of callbacks
> > >
> > >
> > > > A co-worker asked today what they were and why they are so
> > > useful, and to
> > > be
> > > > honest, I struggled in giving a good example. Anyone have a sec
> > > to spare?
> > > >
> > > > Thanks!
> > > > Jack
> > > >
> > > >
> > >
> > >
> >
>
>
>