inheritance.rb

# Ryan Paul, 6/20/15, Sandboxing with ruby
# See bottom for output

# More advanced example on class surfing:
# http://daniel.fone.net.nz/blog/2013/05/27/generating-a-class-hierarchy-in-ruby/

# Interesting discussion on static vs dynamic languages and Modules:
# http://ducktypo.blogspot.com/2010/08/why-inheritance-sucks.html


# C style main block (just cause like, why not)
def main
  # ctor: name
  a = Item.new("Parent")
  a.object_info

  # ctor: name, desc
  b = SubItem.new("Child", "cool!")
  b.object_info
  
  # ctor: name, desc, num
  c = SubSubItem.new("SubChild", "way cooler!", 69)
  c.object_info
end

# Methods we want all classes to have access to
module Utility
  def gen_class_tree obj
    klass = obj.class
    tree = [klass]
    tree << klass while klass = klass.superclass
    tree.reverse.join('::')
  end

  def object_info
    #print "----\n"
    print "#{gen_class_tree self}\n"      # List class hierarchy
    print "#{self.instance_variables}\n"  # List variables
    print "[#{self}]\n"                   # Calls to_s without adding quotes
    print "----\n"                        # Seperator
  end
end

# Base class that has cool custom utility functionality
class Item
  include Utility

  def initialize name 
    @name = name
  end

  def to_s
    "{name: '#{@name}'}"
  end

end


# Sub class
class SubItem < Item

  def initialize name, desc
    super name
    @desc = desc
  end

  def to_s
    super + ", {desc: '#{@desc}'}"
  end

end


# Sub class of sub class
class SubSubItem < SubItem

  def initialize name, desc, num
    super name, desc
    @num = num
  end

  def to_s
    super + ", {num: #{@num}}"
  end

end

# Run main block after classes defined
main()

# OUTPUT:
# 
# BasicObject::Object::Item
# [:@name]
# [{name: 'Parent'}]
# ----
# BasicObject::Object::Item::SubItem
# [:@name, :@desc]
# [{name: 'Child'}, {desc: 'cool!'}]
# ----
# BasicObject::Object::Item::SubItem::SubSubItem
# [:@name, :@desc, :@num]
# [{name: 'SubChild'}, {desc: 'way cooler!'}, {num: 69}]
# ----
# [Finished in 0.0s]