《Effective C++》笔记（一）

1,处理operator new内存分配失败的情况
<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

#include<iostream>
usingnamespacestd;
template<typenameT>
classnewhandlersupport
{//提供类set_new_handler支持的基类
public:
staticnew_handlerset_new_handler(new_handlerp);
staticvoid*operatornew(size_tsize);//重载operatornew运算符
private:
staticnew_handlercurrenthandler;//当前的new_handler
};
template<typenameT>
new_handlernewhandlersupport<T>::set_new_handler(new_handlerp)
{
new_handleroldhandler=currenthandler;
currenthandler=p;
returnoldhandler;
}
template<typenameT>
void*newhandlersupport<T>::operatornew(size_tsize)
{
new_handlerglobalhandler=std::set_new_handler(currenthandler);//申请内存前先设置新的new_Handler
void*memory;
try
{
memory=::operatornew(size);//实际分配内存
}
catch(std::bad_alloc&)
{
std::set_new_handler(globalhandler);//恢复旧的new_handler
throw;//抛出异常
}
std::set_new_handler(globalhandler);
returnmemory;
}
template<typenameT>
new_handlernewhandlersupport<T>::currenthandler=NULL;


classGamePlayer:publicnewhandlersupport<GamePlayer>
{
private:
staticconstintNUM_TURNS;
int*scores;

public:
GamePlayer();
~GamePlayer();
};
constintGamePlayer::NUM_TURNS=5;
GamePlayer::GamePlayer()
{
cout<<"构造函数"<<endl;
scores=newint[NUM_TURNS];
memset(scores,0,sizeof(scores));
for(inti=0;i<NUM_TURNS;++i)
{
scores[i]=i;
}
}
GamePlayer::~GamePlayer()
{
cout<<"析构函数"<<endl;
for(inti=0;i<NUM_TURNS;++i)
{
cout<<scores[i]<<'/t';
}
cout<<endl;
delete[]scores;
scores=NULL;
}
voidnomorememory()
{
cerr<<"unabletosatisfyrequestformemory/n";
abort();
}
intmain()
{
::set_new_handler(nomorememory);
GamePlayer::set_new_handler(nomorememory);
GamePlayer*pPlayOne=newGamePlayer();
deletepPlayOne;
GamePlayer::set_new_handler(NULL);
try
{
GamePlayer*pPlayTwo=newGamePlayer();
deletepPlayTwo;
}
catch(std::bad_alloc&)
{
cerr<<"operatornewfailed"<<endl;
}
system("pause");
return0;
}