From: "Chr. Rippel" <chr_news@...>
Date: 2002-01-15T12:30:27+09:00
Subject: A possible class variable bug? - Re: a wishlist for ruby 2.0

"Mathieu Bouchard" <matju@sympatico.ca> wrote in
....
> * remove Module.constants, which currently calls Object.constants as
> Module#constants on the Object object; doing that would uncover the other
> Module.constants, that is, Module#constants on the Module object.

Well following this logic it might make sense to (re)unfiy the concepts
of class variables and global variables the ladder being class variables
of the class Object.  A somewhat radical version would be the removal of
class variables all together since it's possible to simulate the effect of
class variables using only class instance variables and class accessory
methods (since this has a "pythonish" touch to it surely won't fly;-)
In cvs you get ...

------
class A
  class << self
    attr_accessor :__var
    def var
      A.__var
    end
    def var=(rval)
      A.__var=(rval)
    end
    protected :__var
  end
  self.__var = "A"
  def var
    type.var
  end
end

class B < A
  self.var= "B"
end

puts A.new.var  # => B
puts B.new.var  # => B
------

In the short term it is probably necessary to clarify the following
behavior

-----
class Gods
  @@rule = "Uranus"
  def ruler
    puts @@rule
  end
  def self.ruler
    puts @@rule
  end
end
module Olympians
 @@rule ="Zeus"
 def ruler
    puts @@rule
  end
end
class Titans < Gods
  @@rule = "Cronus"
  include Olympians
end


Gods.new.ruler    # => Cronus
Gods.ruler           # => Cronus
Titans.new.ruler  # => Zeus
Titans.ruler          # => Zeus

-----
verus
-----

class Gods
  @@rule = "Uranus"
  def ruler
    puts @@rule
  end
  class << self
      def ruler
        puts @@rule
      end
  end
end
module Olympians
 @@rule ="Zeus"
 def ruler
    puts @@rule
  end
end
class Titans < Gods
  @@rule = "Cronus"
  include Olympians
end


Gods.new.ruler   # => Cronus
Gods.ruler           # => Cronus
Titans.new.ruler  # => Zeus
Titans.ruler         # => Cronus <=  here is the difference
-----


One possibly  would be the introduction of super class
variables (I am kidding;-)

-----
class Ring_Carrier; end
class Narya_Carrier < Ring_Carrier
  @@@rule ="Gandalf"
  def rule
    @@@rule
  end
end
class Nenya_Carrier < Ring_Carrier
end
class Vilya_Carrier < Ring_Carrier
end

puts Narya_Carrier.new.rule # => Gandalf
# Gandalfs demise
class  Ring_Carrier
  @@@rule ="One variable to rule them, one variable to find them ...\
  and in the darkness bind them."
  def rule
    @@@rule
  end
end

puts Narya_Carrier.new.rule # => One variable to rule them ...
puts Nenya_Carrier.new.rule # => One variable to rule them ...
-----

>
> * Module#included_modules(recurse=true) where
> included_modules(false) would give a list of only _direct_ inclusions.
> This is consistent with Module#instance_methods, except for the default
> value.

A somewhat extend version would be

Module#include_modules(recursion_depth = -1)

with the "depth" logic of Marshal#depth etc. ...

....


/Christoph