From: Curt Hibbs <curt.hibbs@...>
Date: 2005-09-16T00:19:32+09:00
Subject: Re: Get to the Point: Ruby and Rails Presentation Slides

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Ruby uses the same model of method invocation as Smalltalk. Conceptually,=
=20
you send a "message" to an object. The message has a name and a set of=20
parameters. Ruby attempts to find a method definition that matches the=20
signature of the message in the target object's class and each of its=20
superclasses.=20

If no matching method is found, Ruby sends a "method_missing" message to th=
e=20
object instead (including the original message as a parameter). Most object=
s=20
don't implement method_missing and the implementation in Ruby's root object=
=20
is invoked (which output the standard error message).

If the object does implement method_missing, then it gets control and can d=
o=20
whatever it wants with the original message. In the case of this example, i=
t=20
forwards the original message to the object it is proxying.

This is a powerful feature when you are building reusable frameworks. Rails=
=20
uses this to provide "virtual" implementations of its find_* methods.=20
FreeRIDE uses this to implement attributes on its Databus nodes.

Hope that helped.

Curt

On 9/15/05, Josh Charles <josh.charles@gmail.com> wrote:
>=20
> On 9/14/05, John W. Long <ng@johnwlong.com> wrote:
> > Comments and suggestions are welcome. We would like to present this
> > again in the future, so it would be good to clarify things a little.
>=20
> Excellent Presentation. The only thing I didn't quite understand was
> the "method_missing" stuff. I haven't encountered that before; could
> you add to that a little bit?
>=20
> Josh
>=20
>

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