最近多了很多东西要面对，有些事情令我的想法更加多了，感觉对各种事情的看法发生变法了。
可能是每段时期的想法可能都不一样，现在我和一年多的女朋友分手了，反而感觉轻松舒服了许多，也不用想究竟。
好了，感情问题的东西不用多想了。
最近我在学习设计模式，发现Head First设计模式 这本书很好，对比学校的清华教材，学习起来效率很高。
一开始先了解了很多种模式，细读了装饰者模式和观察者模式，如响雷惊耳，原来设计模式讲述的就是解决问题的方法，是前辈们积累下来的经验，让程序变得更可靠，灵活，稳定#￥%……&*的设计。
下面是自己用c++实现的代码，练练手，其中有些提醒自己的小注释，不影响阅读。
Observer:
#include <iostream>
#include <vector>
using namespace std ;
class DisplayElement{
public:
virtual void display() = 0;
};
class Observer{
public:
int index;
virtual void update(int p,int t,int h)= 0; /////////推方式，可观察者通知观察者
virtual void update() = 0; //拉
virtual void setIndex(int) = 0;
virtual int getIndex() = 0;
// virtual void display() = 0;
};
class Observable{
public:
int count;
vector<Observer*> observers; //////////用指针<Observer*>
Observable(int p =0,int t = 0,int h = 0)
{
pressure = p;
temperature = t;
humidity = h;
count = -1;
}
void addObserver(Observer *o)
{
count++;
o->setIndex(count);
observers.push_back(o);
}
void removeObserver(Observer *o)
{
int Index = o->getIndex();
int i = 0;
for(vector<Observer*>::iterator it = observers.begin();it != observers.end();i++)
{
if(i==Index)
observers.erase(it);
else
it++;
}
}
void notifyObservers()
{
//// if(observers.begin()==observers.end()) { cout<<"wtf ,begin == endn"; }
for(vector<Observer*>::const_iterator it = observers.begin();it != observers.end();it++)
{
(*it)->update();//pressure,temperature,humidity); //////////加括号（*iter）
}
}
/* void showObservers()
{
for(vector<Observer*>::iterator it = observers.begin();it != observers.end();it++)
{
(*it)->display();
}
}
*/
void MesurementsChanged(int p,int t,int h)
{
pressure = p;
temperature = t;
humidity = h;
notifyObservers();
}
int getPressure(){return pressure;}
int getTemperature(){return temperature;}
int getHumidity(){return humidity;}
private:
int pressure;
int temperature;
int humidity;
};
class ObserverOne:public Observer,public DisplayElement{
public:
int temperature;
int humidity;
int index;
Observable *observable;
ObserverOne(Observable *observable)
{
this->observable = observable;
observable->addObserver(this);
temperature = 38;
humidity = 70;
index = -1;
}
virtual void setIndex(int i){index = i;}
virtual int getIndex(){return index;}
~ObserverOne()
{
observable->removeObserver(this);
}
virtual void display()
{
cout<<"Current Conditions: "<<temperature<<" F degrees and "
<<humidity<<" % humidity.n";
}
virtual void update(int p,int t,int h)//在“推”过来的数据中选取
{
temperature = t;
humidity = h;
display();
}
virtual void update()//拉 需要的数据过来
{
temperature = observable->getTemperature() *10;
humidity = observable->getHumidity() *10 ;
display();
}
};
int main()
{
Observable theme;
ObserverOne CurrentCondition(&theme);
CurrentCondition.display();
theme.MesurementsChanged(80,37,71);
theme.MesurementsChanged(80,36,73);
theme.MesurementsChanged(80,35,65);
return 0;
}
代码再混乱，只要有图解就很清晰的
Decorator:
#include <iostream>
#include <string>
using namespace std;
class Beverage{
public:
string description;
public:
Beverage(){
description = "Unknown Beverage";
}
virtual const double cost() = 0;
virtual string getDescription(){
return description;
}
};
class DarkRoast:public Beverage{ //深焙咖啡
public:
//// string description;
public:
DarkRoast(){
description = "DarkRoast";
}
const double cost(){
return 0.99;
}
};
class CondimentDecorator:public Beverage{
public:
virtual string getDescription() = 0;
};
class Milk:public CondimentDecorator{ //牛奶
private:
Beverage *beverage;
public:
Milk(Beverage *beverage){
this->beverage = beverage;
}
string getDescription(){
return beverage->getDescription() + ", Milk";
}
const double cost(){
return beverage->cost() + 0.10;
}
};
class Soy:public CondimentDecorator{ //豆浆
private:
Beverage *beverage;
public:
Soy(Beverage *beverage){
this->beverage = beverage;
}
string getDescription(){
return beverage->getDescription() + ", Soy";
}
const double cost(){
return beverage->cost() + 0.15;
}
};
class Whip:public CondimentDecorator{ //奶泡
private:
Beverage *beverage;
public:
Whip(Beverage *beverage){
this->beverage = beverage;
}
string getDescription(){
return beverage->getDescription() + ", Whip";
}
const double cost(){
return beverage->cost() + 0.10;
}
};
class Mocha:public CondimentDecorator{ //摩卡
private:
Beverage *beverage;
public:
Mocha(Beverage *beverage){
this->beverage = beverage;
}
string getDescription(){
return beverage->getDescription() + ", Mocha";
}
const double cost(){
return beverage->cost() + 0.20;
}
};
void display(Beverage* beverage){
cout<<beverage->getDescription()<<' '<<beverage->cost()<<'$'<<endl;
}
int main()
{
Beverage *beverage = new DarkRoast();
display(beverage);
beverage= new Mocha(beverage);
display(beverage);
beverage = new Milk(beverage);
display(beverage);
delete beverage;//最近c++写得少了，连内存都忘记释放了！
return 0;
}
原文链接: https://www.cnblogs.com/Kelvinshere/archive/2013/02/28/2937748.html
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