# composite.bsh
# Compose objects into tree structures to represents part-whole hierarchies.
# Let's clientstreat individual objects and compositions of objects uniformly.
# 1. basic behavior in form of trait-module
module Component
def operation
end
end
module Composite
def initialize
@children = []
end
def <<(component)
@children << component
end
def >>(component)
@children.delete(component)
end
def [](index)
@children[index]
end
def []=(index, value)
@children[index] = value
end
def operation
puts "composite operation"
@children.each {|child| child.operation}
end
def to_s
"children: " + @children.join(', ')
end
end
# 2. implementations
class Leaf
include Component
def initialize(name)
@name = name
end
def operation
puts "leaf operation"
end
def to_s
@name
end
end
class Container
include Component
include Composite
def initialize(name)
super()
@name = name
end
def to_s
"[ name: " + @name + "; children: " + @children.join(', ') + "]"
end
end
# 3. test
container1 = Container.new("c1")
container2 = Container.new("c2")
leaf1 = Leaf.new("l1")
leaf2 = Leaf.new("l2")
leaf3 = Leaf.new("l3")
container1 << container2
container1 << leaf1
container1 << leaf2
container2 << leaf3
puts "Hierarchy: \n" + container1.to_s
puts "-------"
puts "Second element: " + container1[1].to_s
puts "-------"
container1[1] = Leaf.new("l4")
puts "Set second element to: " + container1[1].to_s
puts "-------"
container1 >> leaf1
puts "Hierarchy: \n" + container1.to_s
puts "-------"
puts "Operation on composite: \n"
container1.operation
puts "-------"
