From: Philippe Lang <philippe.lang@...>
Date: 2009-02-17T00:29:14+09:00
Subject: Inherit and override in the same time?

Hi Ruby gurus,

Let's say we have a Parent class, and a Child1 class that inherits from
the Parent class.

I'd like to create a Child2 class that inherits most of the Child1
class, except for one method, which I'd like to override completely. The
problem is that I need to call the method in the Parent class, and
apparently "super.super" is not supported:

----------------------------
class Parent
 def go
   puts 'parent'
 end
end

class Child1 < Parent
 def go
   super
   puts 'child1'
 end
 def a_method_id_like_to_inherit
 end
end

class Child2 < Child1
 def go
   super.super
   puts 'child2'
 end
end

Child2.new.go 
----------------------------
in `go': undefined method `super' for nil:NilClass (NoMethodError)
----------------------------

I ended up doing this, which apprently works.

----------------------------
class Parent
 def go
   puts 'parent'
 end
end

class Child1 < Parent
 def go
   super
   puts 'child1'
 end
 def a_method_id_like_to_inherit
 end
end

class Child2 < Child1
 def go
   self.class.superclass.superclass.instance_method( :go ).bind( self
).call 
   puts 'child2'
 end
end

Child2.new.go 
----------------------------
parent
child2
----------------------------

Isn't there anything simpler than that? Or is that kind of pattern
considered as bad design maybe?

Philippe