From: Logan Capaldo <logancapaldo@...>
Date: 2006-05-25T03:37:39+09:00
Subject: Re: define_method for a single instance?


On May 24, 2006, at 2:18 PM, Jake McArthur wrote:

> I'm trying to define a method for a specific instance of a class  
> rather than for every instance of the class. Basically, something  
> like this:
>
> class A
>   def add_wibble_method
>     # don't know what to do here
>   end
> end
>
> foo = A.new
> bar = A.new
> foo.add_wibble_method
> foo.wibble # should work
> # bar.wibble should not work
>
> Any help would be appreciated.
>
> - Jake McArthur
>

% cat wibble.rb
class A
   def add_wibble
     def self.wibble
       puts "I'm wibbling!"
     end
   end
end

class B
   def add_wibble
     (class << self; self; end).class_eval do
       define_method(:wibble) { puts "I too can wibble." }
     end
   end
end

a = A.new
b = B.new
a.add_wibble
a.wibble
b.add_wibble
b.wibble
begin
a1 = A.new
a1.wibble
rescue => ex
   puts ex
end

begin
   b1 = B.new
   b1.wibble
rescue => ex
   puts ex
end




% ruby wibble.rb
I'm wibbling!
I too can wibble.
undefined method `wibble' for #<A:0x1e89f0>
undefined method `wibble' for #<B:0x1e88ec>