From: Enrique Comba Riepenhausen <ecomba@...>
Date: 2007-05-10T15:56:39+09:00
Subject: The Factory Method

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Hi everyone,

as you know I started a few days ago the Ruby Patterns Wiki and now I  
am starting to put in some samples. As you know, although I am not  
new to software development, I am still a newbie in Ruby.

I was thinking about the Factory Method Pattern and following came to  
my mind. If we follow the Pattern by the book (GoF) we would have  
following code (simplified for the purpose of clarity):

class Product
   def hi
     "hello there"
   end
end

class ConcreteProduct < Product
   def hi
     "Hello from the concrete implementation"
   end
end

class Creator
   def create_product
   end
end

class ConcreteCreator < Creator
   def create_product
     ConcreteProduct.new
   end
end

Obviously this code strikes in Ruby (specially the creator class that  
doesn't make much sense to me). How would you people think this could  
be implemented in Ruby? Or better to say, what is the Ruby way to  
solve this intent of the Factory Method Pattern: Define an interface  
for creating an object, but let subclasses decide which class to  
instantiate. Factory Method lets a class defer instantiation to  
subclasses.

Cheers,

Enrique Comba Riepenhausen
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