From: Philippe Lang <philippe.lang@...>
Date: 2009-02-17T01:26:19+09:00
Subject: Re: Inherit and override in the same time?

Rick DeNatale wrote:

>> 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:

> It's not clear WHY you want to do this but..

Hi Rick and James,

Thanks for your answer.

I tried to rewrite my example so it shows a little bit better WHY I'm
trying to do that. 

------------------------------------

class Form
 def initialize
   puts "form preparation"
 end
 def search_data
   puts "form search preparation"
   yield
   puts "form search cleanup"
 end
end

class ProductForm < Form
 def initialize
   super
   puts "product form widgets preparation"
 end
 def search_data
   super do
    puts "product search"
   end
  end
end

class ArchivedProductForm < ProductForm
 def search_data
   self.class.superclass.superclass.instance_method( :search_data
).bind( self ).call do
     puts "archived product search"
   end
  end
end

ProductForm.new.search_data
puts "------------------"
ArchivedProductForm.new.search_data

------------------------------------
form preparation
product form widgets preparation
form search preparation
product search
form search cleanup
------------------
form preparation
product form widgets preparation
form search preparation
archived product search
form search cleanup
------------------------------------

Basically, a ProductForm or ArchivedProductForm are identical, except
the way they are being searched for. All the rest, like the widgets on
the form, are exactly the same.

I'm pretty sure now I have to refactor somehow my code, to keep things
clean. I guess the following code, with an extra class, is the way to
go:

------------------------------------

class Form
 def initialize
   puts "form preparation"
 end
 def search_data
   puts "form search preparation"
   yield
   puts "form search cleanup"
 end
end

class ProductBaseForm < Form
 def initialize
   super
   puts "product form widgets preparation"
 end
end

class ProductForm < ProductBaseForm
 def search_data
   super do
     puts "product search"
   end
  end
end

class ArchivedProductForm < ProductBaseForm
 def search_data
   super do
     puts "archived product search"
   end
  end
end

ProductForm.new.search_data
puts "------------------"
ArchivedProductForm.new.search_data

------------------------------------
form preparation
product form widgets preparation
form search preparation
product search
form search cleanup
------------------
form preparation
product form widgets preparation
form search preparation
archived product search
form search cleanup
------------------------------------

Best regards,

Philippe