From: Devin Mullins <twifkak@...>
Date: 2005-10-03T03:36:53+09:00
Subject: Re: Eval and block problems

Brian Schr�der wrote:

>and have the block from the dynamically created method foo be
>evaluated in the binding of the instance of A.
>
>I'm sure this is possible, but I've never really grocked eval,
>instance_eval and class_eval.
>  
>
Not sure if this'll help, but it's something I'd thrown together awhile 
back that attempted to the same sorta thing:

module Kernel
  def multidef(name,&blk)
    Multidef.new(self,name).instance_eval(&blk)
    nil
  end
end

class Multidef
  def initialize(receiver, name)
    @receiver = receiver
    name = name.to_s
    @name = name
    @receiver.send(:define_method,name) do |*a|
      send(name+a.size.to_s,*a)
    end
  end
  def args arity, &blk
    name = @name
    @receiver.send(:define_method,@name+arity.to_s,&blk) #do |*a|
#      if a.size != arity then send(name+a.size.to_s,*a)
#      else blk.call(*a) end  #can I get this to execute in self.binding?
#    end
  end
end

multidef :[]= do
  args 2 do |coord,val|
    x,y = convert(coord)
    self[x,y] = val
  end
  args 3 do |x,y,val|
    @thing[x][y] = val
  end
end

class Foo
  multidef :fun do
    args 1 do |a|
      puts "one: #{a}"
    end
    args 2 do |a,b|
      puts "two: #{a}, #{b}"
      fun a
    end
    args 3 do |a,b,c|
      puts "three: #{a}, #{b}, #{c}"
      fun a,b
    end
  end
end

f = Foo.new
f.fun(1)
f.fun('a','b','c')
f.fun('hello',/nightmare/)
__END__

Problems:
1. super doesn't work across different arities.
2. Can't take blocks.

Devin