Lab 2: Template Method

Objectives

During this lab session:

Students will write and test Ruby code that implements the Template Method design 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 templatemethod. Inside this folder, create two files called table_generator.rb, and student.rb. Their initial contents should be as follows. Study them carefully so you understand how they work.

# File name: table_generator.rb

class TableGenerator
  
  def initialize(header, data)
    @header = header
    @data = data    
  end
  
  def generate
    generate_header_row + (@data.map {|x| generate_row(x)}).join
  end
  
  def generate_header_row    
    (@header.map {|x| generate_header_item(x)}).join
  end
  
  def generate_item(item)
    item
  end
  
  def generate_row(row)
    (row.map {|x| generate_item(x)}).join
  end
  
  def generate_header_item(item)
    item
  end
end

class CSVTableGenerator < TableGenerator
  
  def generate_row(row)
    "#{(row.map {|x| generate_item(x)}).join(',')}\n"
  end
  
  def generate_header_row
    generate_row(@header)
  end
    
end

# File name: student.rb

class Student
  
  include Enumerable
  # Note: This class does not support the max, min, or sort methods.
  
  def initialize(id, name, grades)
    @id = id
    @name = name
    @grades = grades    
  end
  
  def inspect
    "Student(#{@id}, #{@name.inspect})"
  end
  
  def grade_average
    @grades.inject(:+)/@grades.size
  end
  
  def each &block
    yield @id
    yield @name
    @grades.each(&block)
    yield grade_average
  end
  
end

The TableGenerator and its subclass CSVTableGenerator are an implementation of the Template Method pattern. Given some tabular data, they allow generating tables in different kinds of text formats. The Student class will be used when doing the tests.

In the table_generator.rb source file, write the following classes: HTMLTableGenerator and LaTeXTableGenerator. These classes must extend TableGenerator and override the appropriate methods so that the following test units work as expected. Place the test class in a source files called test_table_generator.rb.

# File name: test_table_generator.rb

require 'test/unit'
require './table_generator'
require './student'

class TableGeneratorTest < Test::Unit::TestCase
  
  def setup
    @headerNums = %w{Snap Crackle Pop}
    @dataNums = [[10, 20, 30],
                [12, 64, 13],
                [34, 11, 29],
                [99, 15, 34]]
    
    @headerStudents = %w{id name grade1 grade2 grade3 average}
    @dataStudents = [Student.new(123, "Selma Bouvier", [71, 84, 89]),
                     Student.new(241, "Carl Carlson", [78, 85, 90]),
                     Student.new(299, "Todd Flanders", [67, 71, 77]),
                     Student.new(311, "Barney Gumble", [24, 18, 35]),
                     Student.new(427, "Edna Krabappel", [92, 95, 99]),
                     Student.new(666, "Damian Thorn", [66, 66, 66]),
                     Student.new(718, "Manjula Nahasapeemapetilon", [53, 72, 88])]
  end
  
  def test_CSVTableGenerator
    assert_equal \
      "Snap,Crackle,Pop\n" +
      "10,20,30\n" +
      "12,64,13\n" +
      "34,11,29\n" +
      "99,15,34\n",
      CSVTableGenerator.new(@headerNums, @dataNums).generate
    assert_equal \
      "id,name,grade1,grade2,grade3,average\n" +
      "123,Selma Bouvier,71,84,89,81\n" +
      "241,Carl Carlson,78,85,90,84\n" +
      "299,Todd Flanders,67,71,77,71\n" +
      "311,Barney Gumble,24,18,35,25\n" +
      "427,Edna Krabappel,92,95,99,95\n" +
      "666,Damian Thorn,66,66,66,66\n" +
      "718,Manjula Nahasapeemapetilon,53,72,88,71\n",
      CSVTableGenerator.new(@headerStudents, @dataStudents).generate      
  end

  def test_HTMLTableGenerator    
    assert_equal \
      "<table>\n" +
      "<tr><th>Snap</th><th>Crackle</th><th>Pop</th></tr>\n" +
      "<tr><td>10</td><td>20</td><td>30</td></tr>\n" +
      "<tr><td>12</td><td>64</td><td>13</td></tr>\n" +
      "<tr><td>34</td><td>11</td><td>29</td></tr>\n" +
      "<tr><td>99</td><td>15</td><td>34</td></tr>\n" +
      "</table>\n",
      HTMLTableGenerator.new(@headerNums, @dataNums).generate
    assert_equal \
      "<table>\n" +
      "<tr><th>id</th><th>name</th><th>grade1</th>" +
      "<th>grade2</th><th>grade3</th><th>average</th></tr>\n" +
      "<tr><td>123</td><td>Selma Bouvier</td><td>71</td>" +
      "<td>84</td><td>89</td><td>81</td></tr>\n" +
      "<tr><td>241</td><td>Carl Carlson</td><td>78</td>" +
      "<td>85</td><td>90</td><td>84</td></tr>\n" +
      "<tr><td>299</td><td>Todd Flanders</td><td>67</td>" +
      "<td>71</td><td>77</td><td>71</td></tr>\n" +
      "<tr><td>311</td><td>Barney Gumble</td><td>24</td>" +
      "<td>18</td><td>35</td><td>25</td></tr>\n" +
      "<tr><td>427</td><td>Edna Krabappel</td><td>92</td>" +
      "<td>95</td><td>99</td><td>95</td></tr>\n" +
      "<tr><td>666</td><td>Damian Thorn</td><td>66</td>" +
      "<td>66</td><td>66</td><td>66</td></tr>\n" +
      "<tr><td>718</td><td>Manjula Nahasapeemapetilon</td><td>53</td>" +
      "<td>72</td><td>88</td><td>71</td></tr>\n" +
      "</table>\n",
      HTMLTableGenerator.new(@headerStudents, @dataStudents).generate
  end
  
  def test_LaTeXTableGenerator    
    assert_equal \
      "\\begin{tabular}{ | l | l | l | }\n" +
      "\\hline\n" +
      "Snap & Crackle & Pop \\\\\n" +
      "\\hline\n" +
      "\\hline\n" +
      "10 & 20 & 30 \\\\\n" +
      "\\hline\n" +
      "12 & 64 & 13 \\\\\n" +
      "\\hline\n" +
      "34 & 11 & 29 \\\\\n" +
      "\\hline\n" +
      "99 & 15 & 34 \\\\\n" +
      "\\hline\n" +
      "\\end{tabular}\n",
      LaTeXTableGenerator.new(@headerNums, @dataNums).generate    
    assert_equal \
      "\\begin{tabular}{ | l | l | l | l | l | l | }\n" +
      "\\hline\n" +
      "id & name & grade1 & grade2 & grade3 & average \\\\\n" +
      "\\hline\n" +
      "\\hline\n" +
      "123 & Selma Bouvier & 71 & 84 & 89 & 81 \\\\\n" +
      "\\hline\n" +
      "241 & Carl Carlson & 78 & 85 & 90 & 84 \\\\\n" +
      "\\hline\n" +
      "299 & Todd Flanders & 67 & 71 & 77 & 71 \\\\\n" +
      "\\hline\n" +
      "311 & Barney Gumble & 24 & 18 & 35 & 25 \\\\\n" +
      "\\hline\n" +
      "427 & Edna Krabappel & 92 & 95 & 99 & 95 \\\\\n" +
      "\\hline\n" +
      "666 & Damian Thorn & 66 & 66 & 66 & 66 \\\\\n" +
      "\\hline\n" +
      "718 & Manjula Nahasapeemapetilon & 53 & 72 & 88 & 71 \\\\\n" +
      "\\hline\n" +
      "\\end{tabular}\n",
      LaTeXTableGenerator.new(@headerStudents, @dataStudents).generate
  end
end

All Ruby source files created for this lab must start with a comment containing the lab's title, date, and the authors' personal information. For example:
```
# Lab 2: Template Method
# Date: 25-Jan-2011
# Authors:
# 456654  Anthony Stark 
# 1160611 Thursday Rubinstein
```

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 lab2_report_A0MMMMMMM.tex, where A0MMMMMMM is your student ID. From your LaTeX source, generate the corresponding PDF file. That file should be called lab2_report_A0MMMMMMM.pdf. Place these two files in the templatemethod directory.
Create a ZIP file with the full contents of the templatemethod directory. Call this file templatemethod.zip.
Using the Online Assignment Delivery System (SETA), deliver the ZIP file.

Due date is Thursday, January 27.

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 2: Template Method

Objectives

Activity Description

Deliverables

Evaluation