strategy_decorator.rb

module Component
    def operation
        raise "Component error"
    end
end

module Decorator
    include Component
    def initialize(component)
        @component = component
    end
    
    def operation
        @component.operation
    end
    
    def remove
        return @component
    end

end

class Fire
    include Decorator
    def operation
        puts "Fire added"
        super
    end
end

class Ice
    include Decorator
    def operation
        puts "Ice added"
        super
    end
end

class Wizard
    include Component
    
    def initialize(strategy)
        @strategy = strategy
    end
    
    def operation
        @strategy.execute
    end
    
    def change_strategy(strategy)
        @strategy = strategy
    end
end


module MagicStrategy
    def execute
        raise "MagicStrategy error"
    end
end

class Wand
    include MagicStrategy
    def execute
        puts "Wand magic"
    end
end

class Sword
    include MagicStrategy
    def execute
        puts "Sword magic"
    end
end


# use magic strategy
wand_strategy = Wand.new
wizard = Wizard.new(wand_strategy)
wizard.operation

# swap strategy
sword_strategy = Sword.new
wizard.change_strategy(sword_strategy)
wizard.operation

# add types of magic decorators
wizard = Ice.new(Fire.new(wizard))
wizard.operation

# remove decorator
wizard = wizard.remove
wizard.operation

# remove decorator
wizard = wizard.remove
wizard.operation