帮忙看看这个NEW什么意思

houhulou

ACE_Allocator *
ACE_Allocator::instance (void)
{
  //  ACE_TRACE ("ACE_Allocator::instance");

  if (ACE_Allocator::allocator_ == 0)
  {
      // Perform Double-Checked Locking Optimization.
          static void *allocator_instance = 0;

          // Check this critical assumption.  We put it in a variable
          // first to avoid stupid compiler warnings that the
          // condition may always be true/false.
#if !defined (ACE_NDEBUG)
          int assertion = (sizeof allocator_instance ==
                           sizeof (ACE_New_Allocator));
          ACE_ASSERT (assertion);
#endif /* !ACE_NDEBUG */

         ACE_Allocator::allocator_ = new (&allocator_instance) ACE_New_Allocator;
  }

  return ACE_Allocator::allocator_;
}

ACE_Allocator::allocator_ = new (&allocator_instance) ACE_New_Allocator; 中(&allocator_instance) 什么意思

maxxfire

placement new

houhulou

ACE_Allocator::allocator_ = new (&allocator_instance) ACE_New_Allocator
什么意思  就讲讲这一句 还行

foolishx

ACE_Allocator::allocator_ = new (&allocator_instance) ACE_New_Allocator

这个new 是placement new的用法。

它的意思是说：创建一个ACE_New_Allocator对象，并把这个对象放在allocator_instance所在那块内存中，即不再堆里任务分配空间。

anders0913

在事先分配好的一块内存中，创建一个对象~~