From: Dave Thomas <Dave@...>
Date: 2002-05-02T06:37:07+09:00
Subject: Re: is this FAQ material? -> adding instance methods to an object....

patrick-may@monmouth.com (Patrick May) writes:

> I was trying to add instance methods to an object.  I figured this out
> by looking at some library source, but I had problems finding this
> info on ruby talk or in the FAQ.

> I didn't see it when I looked at the FAQ at
> http://www.rubycentral.com/faq/rubyfaq.html

     8.4 What is a singleton method?

     A singleton method is an instance method associated with one
     specific object.

     You create a singleton method by including the object in the
     definition:



     class Foo
     end

     foo = Foo.new
     bar = Foo.new
     def foo.hello
       puts "Hello"
     end
     foo.hello
     bar.hello

     Produces:

     Hello
     prog.rb:10: undefined method `hello' for #<Foo:0x401b5a90> (NameError)

     Singleton methods are useful when you want to add a method to an
     object and creating a new subclass is not appropriate.


I agree the title of this entry isn't the most helpful in the world :)


Dave