From: Edward Faulkner <ef@...>
Date: 2005-09-20T23:57:03+09:00
Subject: Block that takes a block

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How can I make a block that takes a block argument?  This doesn't parse:

myproc =3D proc{|&blk| [1,2,3].each(&blk)}

The main reason I want to do this is to create a method with
'define_method' that takes a block argument. =20

For example, the 'before' method below works fine, until you apply it
to a method that takes a block. =20

class Object
  # Is there a built-in way to do this?
  def metaclass; class << self; self; end; end

  # Call blk before each invocation of method_name
  def before(method_name, &blk)
    oldblk =3D method(method_name)
    metaclass.instance_eval {
      define_method(method_name){|*args|
        blk.call(*args)
        oldblk.call(*args)
      }
    }
  end
end

thanks,
Ed

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