这种操作符重载该如何使用?

这种操作符重载该怎么使用??

C/C++ code

struct small_alloc{    static void* operator new(size_t size)    {        return smallobject_allocator::instance().allocate(size);    }    static void operator delete(void* p, size_t size)    {        smallobject_allocator::instance().deallocate(p, size);    }};