From: Rich Kilmer <rich@...>
Date: 2002-07-25T14:09:50+09:00
Subject: RE: A Code Challenge

Well...here is some Ruby-fu.

It's a bit evil with eval...but it works with both a proc as a parameter
or the block

class Object
  def extend_method(meth, proc=nil, &block)
    proc = block unless proc
    meth = meth.to_s if meth.kind_of? Symbol
    self.instance_eval {
      @___procs___ = {} unless @___procs___
      @___procs___[meth]=proc
    }
    return if respond_to? "__#{meth}__"
    instance_eval <<-EOS
      class << self
        alias_method :__#{meth}__, :#{meth}
        def #{meth}(*args)
          send(:__#{meth}__, *args)
          @___procs___['#{meth}'].call(*args)
        end
      end
    EOS
  end
end


class O
  def x(a)
    puts "do something with #{a}"
  end
end
o = O.new

o.x(1)

p1 = Proc.new { |a| puts "do something wonderful with #{a}" }
o.extend_method(:x, p1)
o.x(2)

o.extend_method(:x) { |a| puts "do something sweet with #{a}" }
o.x(3)

-rich
> -----Original Message-----
> From: Tom Sawyer [mailto:transami@transami.net]
> Sent: Wednesday, July 24, 2002 11:56 PM
> To: ruby-talk ML
> Subject: A Code Challenge
> 
> Problem:
> 
>   given a proc p and an object o with method x, such that the arity of
x
> and p are the same, dynamically append p into x.
> 
> statically you have this:
> 
>   class O
>     def x(a)
>       puts "do something with #{a}"
>     end
>   end
>   o = O.new
> 
> then given:
> 
>   p = Proc.new { |a| puts "do something else with #{a}" }
> 
> the goal is to dynamically modify instance o such that it were AS IF
it
> were an instantiation of:
> 
>   class O
>     def x(a)
>       puts "do something with #{a}"
>       puts "do something else with #{a}"
>     end
>   end
> 
> ~transami
>