CSC/ECE 517 Summer 2008/wiki1 8 dm

Prototype-based Programming

In Lecture 7, we consider prototype-based programming in Ruby. The example that is given is some what artificial. Can you identify real tasks that are easier with prototype-based programming than with class-based programming? Give the code, at least in outline.

A prototype-based programming approach in Ruby can be viewed as a creating a basic object with the functionality that is desired. Once you've created one version of the object, you can then extend that object into much more complex object. While structural classes can handle the objects, this is simply more efficent to create what you want.

In the case of a container class, for example a linked list, the node object has to handle a number of different objects. So declaring a basic node, and then copying it for typed nodes or more complicated logic like back linked list.

Ex.

|class LinkNode
| attr_reader :name, :next, :value
|
| def initialize(name, next,value)
|   @name, @next, @value = name, next, value
| end
| by
| def getNext
|   next
| end
|end
|
|node1 = LinkNode.new('Dave',nul,nul)
|node2 = LinkNode.new('John,nul,nul)
|
|module StringNode
|  def isEmptyString?
|    if value == nul
|     true
|    else
|      false 
|    end
|end
|
|node1.extend(StringNode)

References

1. Taw's Blog
2. Softpanorama
3. Wikipedia Prototype Programming