Lab 8: Meta-programming Pattern

Objectives

During this lab session:

Students will write and test Ruby code that implements the Meta-programming pattern.

This activity helps students develop the following skills, values and attitudes: ability to analyze and synthesize, capacity for identifying and solving problems, and efficient use of computer systems.

Activity Description

The lab activities can be developed individually or in pairs.

The lab report must be developed individually.

Create a folder called metaprogramming. Inside this folder, create two files called: attr_init.rb and test_attr_init.rb.

All Ruby source files must start with a comment containing the lab's title, date, and the authors' personal information. For example:
```
# Lab 8: Meta-programming Pattern
# Date: 22-Mar-2011
# Authors:
# 456654  Anthony Stark 
# 1160611 Thursday Rubinstein
```
In the attr_init.rb source file, open the Object class and define a new class method called attr_init. This method should work as a class annotation that defines the initialize method in the enclosing class, and also calls the attr_accessor as shown as follows.

Given the class definition:
```
class C
  attr_init :w, :x, :y, :z
end
```
It should be transformed into something equivalent to this:
```
class C
  def initialize(w, x, y, z)
    @w = w
    @x = x
    @y = y
    @z = z
  end
  attr_accessor :w, :x, :y, :z
end
```
Use the meta-programming pattern, as explained in page 309 of [OLSEN], to do this.

The following unit tests verify the correct definition of the attr_init class annotation. Place the test class in the test_attr_init.rb source file.

require 'test/unit'
require './attr_init'

class AttrInitTest < Test::Unit::TestCase
  
  class Alpha
    attr_init :beta, :gamma, :delta
  end
  
  class BiologicalClassification
    attr_init :kingdom, :phylum, :klass, :order, :family, :genus, :species
  end    

  def test_alpha    
    alpha = Alpha.new('one', 'two', 'three')
    assert_equal 3, alpha.method(:initialize).arity
    assert_respond_to alpha, :beta
    assert_respond_to alpha, :beta=
    assert_respond_to alpha, :gamma
    assert_respond_to alpha, :gamma=
    assert_respond_to alpha, :delta
    assert_respond_to alpha, :delta=
    assert_equal 'one', alpha.beta
    assert_equal 'two', alpha.gamma
    assert_equal 'three', alpha.delta
    assert_equal 1, (alpha.beta = 1)
    assert_equal 2, (alpha.gamma = 2)
    assert_equal 3, (alpha.delta = 3)
    assert_equal 1, alpha.beta
    assert_equal 2, alpha.gamma
    assert_equal 3, alpha.delta
  end
  
  def test_biological_classification
    platapus = BiologicalClassification.new(
      'Animalia',
      'Chordata',
      'Mammalia',
      'Monotremata',
      'Ornithorhynchidae',
      'Ornithorhynchus',
      'Ornithorhynchus Anatinus')
    assert_equal 7, platapus.method(:initialize).arity
    assert_respond_to platapus, :kingdom
    assert_respond_to platapus, :phylum
    assert_respond_to platapus, :klass
    assert_respond_to platapus, :order
    assert_respond_to platapus, :family
    assert_respond_to platapus, :genus
    assert_respond_to platapus, :species
    assert_respond_to platapus, :kingdom=
    assert_respond_to platapus, :phylum=
    assert_respond_to platapus, :klass=
    assert_respond_to platapus, :order=
    assert_respond_to platapus, :family=
    assert_respond_to platapus, :genus=
    assert_respond_to platapus, :species=
    assert_equal 'Animalia', platapus.kingdom
    assert_equal 'Chordata', platapus.phylum
    assert_equal 'Mammalia', platapus.klass
    assert_equal 'Monotremata', platapus.order
    assert_equal 'Ornithorhynchidae', platapus.family
    assert_equal 'Ornithorhynchus', platapus.genus
    assert_equal 'Ornithorhynchus Anatinus', platapus.species
    assert_equal 'Amoebozoa', (platapus.kingdom = 'Amoebozoa')
    assert_equal 'Tubulinea', (platapus.phylum = 'Tubulinea')
    assert_equal 'Tubulinida', (platapus.order = 'Tubulinida')
    assert_equal 'Amoebidae', (platapus.family = 'Amoebidae')
    assert_equal 'Amoeba', (platapus.genus = 'Amoeba')
    assert_equal 'Amoeba Proteus', (platapus.species = 'Amoeba Proteus')
  end
  
  def test_errors
    assert_raise(ArgumentError) do
      alpha = Alpha.new()
    end    
    assert_raise(ArgumentError) do
      alpha = Alpha.new(1, 2, 3, 4)
    end    
    assert_raise(ArgumentError) do
      alpha = BiologicalClassification.new()
    end
    assert_raise(ArgumentError) do
      alpha = BiologicalClassification.new(
        'Plantae',
        'Magnoliophyta',
        'Magnoliopsida',
        'Rosales',
        'Rosaceae')
    end
  end
  
end

Deliverables

To hand in your individual lab work, follow these instructions.

Write your lab report according to the specified guidelines. Name your LaTeX source file lab8_report_A0MMMMMMM.tex, where A0MMMMMMM is your student ID. From your LaTeX source, generate the corresponding PDF file. That file should be called lab8_report_A0MMMMMMM.pdf. Place these two files in the metaprogramming directory.
Create a ZIP file with the full contents of the metaprogramming directory. Call this file metaprogramming.zip.
Using the Online Assignment Delivery System (SETA), deliver the ZIP file.

Due date is Monday, March 28.

Evaluation

This activity will be evaluated using the following criteria:

50%	Implementation of functional requirements.
50%	Lab report.
DA	The program and/or report was plagiarized.

Software Design and Architecture

Lab 8: Meta-programming Pattern

Objectives

Activity Description

Deliverables

Evaluation