From: Kent Dahl <kentda@...>
Date: 2002-07-23T20:06:14+09:00
Subject: Re: define_method with super in the proc

Tom Sawyer wrote:
> the problem is that #makeproc is interpreting the super for itself and
> thus reports an error of 'makeproc' super: no superclass method
> 'makeproc' (NameError). obviously that's not what i want. how strange.
> it dosen't try to define @y = 10 for makeproc's object.

Even worse, it seems to define @y = 10 for the class object B. In fact,
you're not getting tied to the makeproc's object, you're getting tied to
the class object B itself.

I expanded on your example:
  class A
    attr_reader :x, :y
    def doit
      @x = 5  
      puts "A.doit"
    end
  end
  
  def makeproc 
    Proc.new {
      @y = 10
      puts "B.doit " + self.inspect
    }
  end
  
  B = Class.new(A)
  B.class_eval {
    alias  doit_super_A doit 
    define_method(:doit, makeproc ) 
  }
  b = B.new
  b.doit                   #=> B.doit B
  puts b.y                 #=> nil
  puts B.instance_eval{@y} #=> 10

By the output of "b.doit", you see that the proc is executed in the
context of the class object B, and not the instance.

Is this a bug? It violates my PoLS atleast. I'm running 
ruby 1.6.6 (2001-12-26) [i586-linux-gnu] and
ruby 1.6.7 (2002-03-01) [i686-linux]


> how do i work
> around this?

I was going to suggest passing :doit_super_A into the makeproc and using
self.send, but in light of the above that won't help much.

*back to scratching head*

-- 
(\[ Kent Dahl ]/)_    _~_    __[ http://www.stud.ntnu.no/~kentda/ ]___/~
 ))\_student_/((  \__d L b__/  NTNU - graduate engineering - 4. year  )
( \__\_�|�_/__/ ) _)Industrial economics and technological management(
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