Big talk design pattern C + + Implementation-6th chapter-Decorative Mode

First, UML diagram

Second, the concept

Decorating mode: Dynamically adds some additional responsibilities to an object, and the adornment mode is more flexible than generating subclasses for added functionality.

Third, the description

Role:

(1)Component is defined as an object that can dynamically add responsibilities to these objects.

(2)concretecomponent is defined as a specific object, it can also add some responsibilities to the object.

(3)Decorator, Decorative abstract class, inherited the component, from the outer class to extend the function of component class, but for component, there is no need to know the existence of Decorator.

(4) As for the Concretedecorator is the specific decorative objects, play a role to add responsibility to component.

When to use:

(1) need to be in the internal assembly to complete the display of the situation.

(2) similar to the builder model, but the requirements of the builder pattern must be stable, while the construction of the decoration pattern is unstable.

(3) We need to put the required functions in the correct sequence in series to control.

Advantages:

(1) The decoration function of the class is removed from the class, so that the original class can be simplified.

(2) effectively distinguish the core functions of the class from the decoration function, and can remove the repetitive decoration logic in the related class.

Iv. implementation of C + +

(1) Conponent is the Concretecomponent class: Here is the person class

#ifndef person_h#define person_h#include <string> #include <iostream>//concretecomponent is Componentclass Person{private:std::string Name;public:person () {}; Person (std::string name) {this->name=name;} virtual void Show () {std::cout<< "decorated" <<name<<std::endl;}}; #endif

(2) Decorator and Concretedecorator: Here is finery and its subclasses

#ifndef finery_h#define finery_h#include <iostream> #include "Person.h"//decorator class Finery:public person{ protected:person* component;public:void Decorator (person* component) {this->component=component;} void Show () {if (component!=null) component->show ();}};/ /Below is a series of Concretedecorator class Tshirts:public finery{public:void Show () {std::cout<< "Big T-shirts"; Finery::show ();}};/ /concretedecorator class Bigtrouser:public finery{public:void Show () {std::cout<< "Down pants"; Finery::show ();}};/ /concretedecorator class Sneakers:public finery{public:void Show () {std::cout<< "Broken Sneakers"; Finery::show ();}};/ /concretedecorator class Suit:public finery{public:void Show () {std::cout<< "Suit"; Finery::show ();}};/ /concretedecorator class Tie:public finery{public:void Show () {std::cout<< "Tie"; Finery::show ();}};/ /concretedecorator class Leathershoes:public finery{public:void Show () {std::cout<< "Leather shoes"; Finery::show ();} }; #endif

(3) Client:main

#include "Finery.h" #include <string> #include <iostream>//client void Main () {person* xc=new person ("side dish"); STD: :cout<< "First dress up:" <<std::endl; sneakers* pqx=new sneakers (); bigtrouser* kk=new Bigtrouser (); tshirts* dtx=new tshirts ();p qx->decorator (XC), Kk->decorator (PQX);d tx->decorator (KK);d tx->show (); STD: :cout<< "Second Dress up:" <<std::endl; leathershoes* px=new leathershoes (); tie* ld=new Tie (); suit* xz=new Suit ();p x->decorator (XC); Ld->decorator (px); xz->decorator (LD); Xz->show ();std::cout< < "" <<std::endl;system ("pause");

Five, the output

Big talk design pattern C + + Implementation-6th chapter-Decorative Mode