decorator c++ design pattern

decorator.cc

#include <iostream>
#include <string>
#include <memory>
#include <string.h>

class AddOn {
	public:
		explicit  AddOn(std::string description) { description_ = description; }
		~AddOn() = default;

		std::string getDescription() { return description_; }

	private:
		std::string description_;
};

class Beverage {
	public:
		explicit Beverage(std::string description, std::shared_ptr<AddOn> &addon): description_(description), addon_(addon) { }
		~Beverage() = default;

		std::string getDescription() { return description_; }
		std::string getAddOn() { return addon_->getDescription(); }

		virtual double cost() = 0;

	private:
		std::string description_;
		std::shared_ptr<AddOn> addon_;
};

class Sugar : public AddOn {
	public:
		explicit Sugar() : AddOn("Sugar") { }
		~Sugar() = default;
};

class Milk : public AddOn {
	public:
		explicit Milk() : AddOn("Milk") { }
		~Milk() = default;
};

class HouseBlend : public Beverage {
	public:
		explicit HouseBlend(std::shared_ptr<AddOn> addon) : Beverage("HouseBlend", addon) { }
		virtual ~HouseBlend() { }

		double cost() { return 100; }
};

class DarkRoast : public Beverage {
	public:
		explicit DarkRoast(std::shared_ptr<AddOn> addon) : Beverage("DarkRoast", addon) { }
		virtual ~DarkRoast() { }

		double cost() { return 200; }
};


int main(int argc, char **argv)
{
	std::unique_ptr<Beverage> bev;
	if (!strcmp(argv[1], "houseblend")) {
		if (!strcmp(argv[2], "milk")) {
			bev = std::make_unique<HouseBlend>(std::make_shared<Milk>());
		}
	} else if (!strcmp(argv[1], "darkroast")) {
		if (!strcmp(argv[2], "sugar")) {
			bev = std::make_unique<DarkRoast>(std::make_shared<Sugar>());
		}
	}

	printf("cost of bev(%s) with (%s): %f\n", bev->getDescription().c_str(), bev->getAddOn().c_str(), bev->cost());

	return 0;
}