From: "R. Kumar" <sentinel.2001@...>
Date: 2010-01-31T16:44:36+09:00
Subject: Inheritance related problem

Note: this is *not* a ruby bug. its a general query.
Perhaps best explained with sample code.

#!/usr/bin/env ruby -w

class Parent
  def printa arg
      puts "inside parent printa #{arg} "
      printb arg
  end
  def printb arg
      puts "inside parent printb #{arg} "
      puts "--> #{arg} "
  end
end

class Child < Parent
  def printa arg
      puts "inside child printa #{arg} reduced 1 "
      # 1 is actually some other instance level variable
      super arg-1
  end
  def printb arg
      puts "inside child printb #{arg}  reduced 1"
      super arg-1
  end
end

if __FILE__ == $0
  begin
      p = Parent.new
      c = Child.new
      puts " parent calls with 5 and 6"
      p.printa 5
      #p.printb 6
      puts " === child calls with 7 === "
      c.printa 7
      #c.printb 7
  ensure
  end
end


Class Child extends Parent. It extends 2 methods by modifying the
incoming parameter and then calling super. One of these methods printa
calls printb.

When Parent's printa is called, it calls it own printb.
However, when Child's printa is called, it calls Parent's printa, which
(in this case) i was hoping would call Parent's printb directly. But it
(correctly) calls Child's printa which once again reduces the arg.

So my arg gets reduced twice. I suppose i could use some flags to
prevent this, But is there any direct way i can coerce Parent printa to
call only Parent printb.

When you execute the above code, you will see that 7 gets decremented 2
times.

Attachments:
http://www.ruby-forum.com/attachment/4448/test.rb

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