monday.rb

MetaprogrammingRuby.rb

#!/usr/bin/env ruby

# object_model/alphanumeric.rb
require "test/unit"

class String
  def to_alphanumeric
    gsub(/[^\w\s]/,'')
  end  
end

class ToAlphanumericTest < Test::Unit::TestCase
  def test_strips_non_alphanumeric_characters
    assert_equal '3 the Magic Number', '3#, the *Magic, Number*?'.to_alphanumeric
  end
end


# object_model/replace.rb
require "test/unit"

class Array
  def substitute(from, to)
    each_with_index { |e, i| self[i] = to if e == from }
  end
end

class ReplaceTest < Test::Unit::TestCase  
  def test_replace
    book_topics = ['html', "java", 'css']
    book_topics.substitute('java', 'ruby')
    expected = ['html', 'ruby', 'css']

    assert_equal(expected, book_topics)
  end
end

puts [].methods.grep(/^re/).inspect


3.times do
  class C
    puts "Hello"
  end
end

class D
  def x; 'x'; end
end

class D
  def y; 'y'; end
end

p D.new.x
p D.new.y


# gems/money-2.1.3/lib/money/core_extensions.rb
class Numeric
  def to_money
    Money.new(self * 100)
  end
end

Money = Struct.new(:cents)

cents = 9999
bargain_price = Money.new(cents) #<struct Money cents=9999>
standard_price = 100.to_money #<struct Money cents=10000>

class MyClass
  def my_method
    @v = 1
  end
end

obj = MyClass.new
puts obj.class # MyClass
puts obj.my_method # 1
puts obj.instance_variables # @v

is_inherited = false
puts Class.instance_methods(is_inherited).inspect  # [superclass, allocate, new]

p String.superclass # Object
p String.ancestors # [String, Enumerable, Comparable, Object, Kernel]
p Enumerable.class # Module
p Class.ancestors # [Class, Module, Object, Kernel]


module MyModule
  MyConstant = "Outer constant"
  
  class MyClass
    MyConstant = "Inner Constant"
    
    module M2
      Module.nesting
    end
  end
end

p MyModule::MyConstant
p MyModule::MyClass::MyConstant
p ::MyModule::MyConstant # absolute


class MyClass; end
obj1 = MyClass.new
obj2 = MyClass.new
obj2.instance_variable_set("@x", 10)
puts obj2.instance_variables


# object_model/lookup.rb
class MyClass
  def my_method
    'my method'
  end
end

class MySubclass < MyClass
end

obj = MySubclass.new
puts obj.my_method


# object_model/lookup_modules.rb
module M
  def m_method
    puts "instance method from module M"
  end
end

class C
  include M
end

C.new.m_method


# object_model/tangle.rb
module Printable 
  def print
    puts "print from Printable"
  end

  def prepare_cover
    puts "prepare_cover from Printable"
  end 
end

module Document 
  def print_to_screen
    prepare_cover 
    format_for_screen
    print
  end

  def format_for_screen 
    puts "format_for_screen"
  end

  def print 
    puts "print from document"
  end 
end

class Book 
  include Document 
  include Printable
  # ...
end

b = Book.new
b.print_to_screen