Strategy策略模式是在模板方法模式上的一個改進(jìn)，模板方法模式是代碼復(fù)用，這里用組合來解決將變化的代碼從“堅(jiān)持相同的代碼”中分開，從而產(chǎn)生Strategy策略模式。 示例代碼：
 #include <iostream>
using namespace std;

class NameStrategy{
public:
   virtual void greet() = 0;
};

class SayHi:public NameStrategy{
public:
   void greet(){cout <<"Hi!How's it going?"<<end;}
};

class Ignore:public NameStrategy{
public:
   void greet(){cout << "(Pretent I don't see you)" <<endl;}
};

class Admission:public NameStrategy{
public:
   void greet(){cout<<"I'm sorry.I forgot your name."<<endl;}
};

//The "Context" controls the strategy:
class Context{
   NameStrategy& strateagy;
pubic:
   Context(NameStrategy& strat):strategy(strat){}
void greet()
   {strategy.greet();}
};

int main()
{
   SayHi  sayhi;
   Ignore ignore;
   Admission admission;
   Context c1(sayhi),c2(ignore),c3(admission);
   c1.greet();
   c2.greet();
   c3.greet();
}
在main（）中就可以看到，運(yùn)行時的策略選擇。

Chain of Responsibility職責(zé)鏈模式可看作是一個策略對象的遞歸調(diào)用，本質(zhì)是嘗試多個解決方法，直到找到一個起作用的。實(shí)際上它是個鏈表，可動態(tài)創(chuàng)建。這里我們可以用STL來實(shí)現(xiàn)。
示例代碼：
#include <iostream>
#include <vector>
using namespace std;

enum Answer(NO.YES);

class GimmeStrategy{
public:
   virtual Answer canIHave()=0;
   virtual ~GimmeStrategy();
};

class AsdRom:public GimmeStrategy{
public:
   Answer canIHave(){
      cout << "Moom?Can I have this?"<<endl;
      return NO;}
};

class AsdDad:public GimmeStrategy{
public:
Answer canIHave(){
   cout << "Dad,I really need this!" <<endl;
   return NO;}
};

class AsdGrandpa:public GimmeStrategy{
public:
   Answet canIHave(){
   cout<<"Grandpa.is it my birthday yet?"<<endl;
   return YES;}
};

class Gimme:public GimmeStrategy{
   vector<GimmeStrategy*> chain;
public:
   Gimme(){
   chain.push_back(new AskMom());
   chain.push_back(new AskDad());
   chain.push_back(new AskGrandpa());
   chain.push_back(new AskGrandma());
}
Answer canIHave(){
   vector<GimmeStrategy*>::iterator it = chain.begin();
   while(it != chain.end())
      if(*it++)->canIHave()==YES)
         return YES;

   cout << "Whiiiiinne!"<<endl;
   retunr NO;
} 
   ~Gimme(){purge(chain);}
};

int main()
{
   Gimme chain;
   chain.canIHave();
}
在GOF的原著中，側(cè)重于鏈表的創(chuàng)建，由于STL的存在，創(chuàng)建鏈表變得很輕松。