From: Eustaquio Rangel de Oliveira J <eustaquiorangel@...>
Date: 2006-03-26T23:45:10+09:00
Subject: Re: Object methods

Hi Robert!

> > s.class.class_eval %q(def x.says() puts "x
> says:"+self
> > end)
> This doesn't work for me.  You define a method "say"
> for an instance "x" 
>   in the scope of the class.  You probably want
> something else.

I noticed that I made a mistake there and correct it
on another email few seconds after that one. Sorry
about that. My fault.

As I told on the other email, the correct thing is

s.class.class_eval %q(def s.says() puts "s says:"+self
end)

So I create a method "says" only on the object s (not
on the class String where it belongs to).

> It would certainly help if you tell us what problem
> you are trying to solve.

Ok, not really a problem, I was just curious about it.


Let's imagine that I need a way to create methods on
*specific objects*, not on their classes. The methods
are stored on some file or the user type it when using
the program (ok, I know the security concerns about
that :-), and I find them later using some reflection
and respond_to calls. 

So at some point the user knows (again, don't know if
its a valid situation) that there are some String
objects hangin' there, s and x, and says "hey, add
this method I defined here on this text field, as a
string, to the s object, but *just to it*, not to its
class or other String objects". On this case, knowing
that I want to create the method just on s, and it's a
String, I can use

String.class_eval %q(def s.says() puts "s says:"+self
end)

to make this works, and ask for some reavaliation of
the current objects, where it will tell me that the s
object, yes, have a "says" method there.

s.respond_to?(:says)

It works this way, I was just curious if there is not
an *object method* to do that, not using the class to
make it works. But works this way because of the need
to add a virtual class to s to hold the says() method,
right?

Best regards,


----------------------------
Eust�quio "TaQ" Rangel 
eustaquiorangel@yahoo.com
http://beam.to/taq 
Usu�rio GNU/Linux no. 224050