From: Stefano Crocco <stefano.crocco@...>
Date: 2008-01-10T19:12:10+09:00
Subject: Re: how to remove a method from an object ?

Alle giovedì 10 gennaio 2008, Valerio Schiavoni ha scritto:
> hello everyone,
>
> how can I remove a method from an object, without impacting future
> instances of its class ?
>
> say:
>
> class Server
>    def print
>        puts 'hello'
>    end
> end
>
> s1 = Server.new
> s1.print #this work
>
> #now remove print from s1 somehow..
>
> s1.print #this should hit method_missing
>
> s2 = Server.new
> s2.print # this should work fine as well...
>
>
>
> Thanks for any help

This should work:

class Server
   def print
       puts "hello from #{object_id}"
   end
end

s1 = Server.new
s1.print

class << s1
  undef_method :print
end

s2 = Server.new
s2.print
begin s1.print
rescue NoMethodError
  puts "undefined method 'print' for #{s1.object_id}"
end

=>
hello from -605995538
hello from -605995648
undefined method 'print' for -605995538

As you can see from the ids displayed by the print method, after removing the 
method from the singleton class of s1, only the call to s2.print works; the 
call to s1.print raises a NoMethodError exception.

I hope this helps

Stefano