关于针对class自定义new操作符失败的函数处理

Posted 2020-08-14 指尖上的快乐

#include <iostream>
#include <new>
using namespace std;

class CSaveCurHandler //用于管理new_handler,保存原始的new_handler,在new成功结束后还原.
{
private:
	new_handler cur;
public:
	CSaveCurHandler(new_handler nh) :cur(nh){}

	~CSaveCurHandler()
	{
		set_new_handler(cur);
	}
};


template<class T>
class CWidget
{
private:
	static new_handler cur_handler;
public:
	static void set_handler(new_handler nh)
	{
		cur_handler = nh;
	}

	static void *operator new(size_t size) throw(std::bad_alloc)
	{
		CSaveCurHandler sch(set_new_handler(cur_handler)); //将原始的保存至CSaveCurHandler对象中
		return ::operator new(size);                       //,调用系统原始的new,返回后自动还原new_handler
	}
};

void outMen()
{
	cout << "内存不够";
}

template<class T>
new_handler CWidget<T>::cur_handler = outMen;

class MY : public CWidget<MY>
{
private:
	char buf[1025 * 1024 * 1024];
};

int main()
{
	MY::set_handler(outMen);

	while (1)
		MY *p = new MY;


	cin.get();
	return 0;
}