From: Oliver Beddows <oliver@...>
Date: 2002-04-10T05:06:51+09:00
Subject: ruby + Creating and extending XML documents

Hi,
	I am looking for some advice / opinion.  I am currently developing a website 
using postgresql + ruby + xml and sablotron. A lot of the time each script on 
the site will require a set of common xml data.  What follows below is my 
attempt at creating a class that will hold and display that data.  Then for 
each page I simply extend the class to include new data.

I`m pretty new to Object Orientation, so am I being naive?
Is my approach totally off the mark?
Have I been smoking too many drugs?
Your opinions please!

Regards,
oliver@jellytone.com
	 
# For example, take the following xml document:
<!--  Master.xml -->
<?xml version='1.0' encoding='UTF-8'?>
<document>
	<data>
		<title>A Page On My Site</title>
		<user>
			<id>1</id>
			<name>oliver</name>
			<password>12345678</password>
			<group>staff</group>
			<is_logged_in>true</is_logged_in>
			<number_of_logins>99</number_of_logins>
		</user>
	</data>
</document>

# And in order to build that document I create this class:
class MasterDocument
	def initialize
		@title = "No Title"
	end
	
	def document
		"<document>#{data}</document>"
	end

	def data
		[ title, user ]
	end

	def title=(newTitle)
		@title = newTitle
	end

	def title
		"<title>#{@title}</title>"
	end

	def user=(newUser)
		@user = newUser
	end

	def user
		if @user.nil? then
			@user = User.new
		end
		"<user><id>#{@user.id}</id>...etc...etc</user>"
	end
end

# So when I need to create a document I do:
xml = MasterDocument.new
xml.title = "A Page On My Site"
xml.user  = user
puts xml.document

# And if I want the document to contain more data I do the following:
class AnotherDocument < MasterDocument
	def initialize
	end

	def data
		super + [ some_data ]
	end

	def some_data=(newSomeData)
		@some_data = newSomeData
	end

	def some_data
		"<some_data>#{@some_data}</some_data>"
	end		
end

# And to implement it I do:
xml = AnotherDocument.new
xml.title     = "ruby review"
xml.user      = user
xml.some_data = "ruby kicks ass"

# Which gives me the following xml document:
<!--  AnotherDocument.xml -->
<?xml version='1.0' encoding='UTF-8'?>
<document>
	<data>
		<title>ruby review</title>
		<user>
			<id>1</id>
			<name>oliver</name>
			<password>12345678</password>
			<group>staff</group>
			<is_logged_in>true</is_logged_in>
			<number_of_logins>99</number_of_logins>
		</user>
		<!-- New data goes here... -->
		<some_data>ruby kicks ass</some_data>
	</data>
</document>