new_handler 问题的笔记

void outOfMem() 
{ 
    std::cout << "Unable to satisfy request for memory\n"; 
    std::abort(); 
} 
int main() 
{ 
    std:: set_new_handler (outOfMem); 
    int* pBigDataArray = new int[1000000000000L]; 

}

不太懂这里为什么调用set_new_handler就能保存outOfMem感觉好奇怪，看了下VS里面源码发现了

// handler.cpp -- set_new_handler for Microsoft
#include <new>


typedef int (__cdecl *new_hand)(size_t);
new_hand __cdecl _set_new_handler(new_hand);


_STD_BEGIN
static new_handler _New_handler; //保存了set_new_handler传进来的参数


int __cdecl _New_handler_interface(size_t) _THROW1(std::bad_alloc)
{ // interface to existing Microsoft _callnewh mechanism
_New_handler();
return (1);
}


_CRTIMP2 new_handler __cdecl set_new_handler(new_handler pnew) _THROW0()
{ // remove current handler
_BEGIN_LOCK(_LOCK_MALLOC) // lock thread to ensure atomicity
new_handler pold = _New_handler;
_New_handler = pnew;//保存函数
_set_new_handler(pnew ? _New_handler_interface : 0);
return (pold);
_END_LOCK()
}


new_handler _CRTIMP2 __cdecl set_new_handler
( 
    int pnh 
) throw()
{
return set_new_handler(static_cast<new_handler>(NULL));
}


_STD_END

每次调用自定义的函数给set_new_handler后，都会把参数的函数传给静态函数_New_handler ，这样new失败后，每次都调用_New_handler函数，就可以做到设置自定义函数来处理new失败的情形