Ruby的装饰器模式实现

class Tree
def initialize
puts "Make a normal tree"
end
def decorate
puts "Make sure the tree won\'t fall"
end
end
class RedBalls < Tree
def initialize(tree)
@parent = tree;
end
def decorate
@parent.decorate
puts "Put on some red balls"
end
end
class BlueBalls < Tree
def initialize(tree)
@parent = tree;
end
def decorate
@parent.decorate
puts "Add blue balls"
end
end
class Angel < Tree
def initialize(tree)
@parent = tree;
end
def decorate
@parent.decorate
puts "An angel on the top"
end
end
tree = Angel.new(BlueBalls.new(RedBalls.new(Tree.new)))
tree.decorate