__STL_TRY和__STL_UNWIND这两个宏的意思

[hualibinbin]

void fill_initialize(size_type n, const T& value) {
empty_initialize();
__STL_TRY {
insert(begin(), n, value);
}
__STL_UNWIND(clear(); put_node(node));
}
这是stl中fill_initialize的源代码，其中__STL_TRY和__STL_UNWIND是不是和try、catch的功能类似，为什么__STL_TRY后面的代码用花括号括起来，而__STL_UNWIND后面的代码则用小括号括起来呢

[龙哥依旧]

这是大师级别研究的东西！

[wokonglinglude]

#define __STL_TRY


Definition at line 230 of file stl_config.h.

Referenced by rb_tree::__copy, __uninitialized_copy_copy, __uninitialized_copy_fill, __uninitialized_copy_n, __uninitialized_fill_copy, vector< node *, Alloc >::allocate_and_copy, vector< node *, Alloc >::allocate_and_fill, hashtable::copy_from, rb_tree< key_type, value_type, select1st< value_type >, key_compare, Alloc >::create_node, slist::create_node, list::create_node, deque::deque, slist::fill_initialize, list::fill_initialize, vector::insert, vector::insert_aux, hashtable< Value, Value, HashFcn, identity< Value >, EqualKey, Alloc >::new_node, priority_queue::pop, priority_queue::push, rope::push_front, slist::range_initialize, list::range_initialize, rb_tree< key_type, value_type, select1st< value_type >, key_compare, Alloc >::rb_tree, hashtable::resize, rope::rope, rope::RopeLeaf_from_unowned_char_ptr, temporary_buffer::temporary_buffer, and deque::~deque.


#define __STL_UNWIND ( action )


Definition at line 234 of file stl_config.h.

Referenced by rb_tree::__copy, __uninitialized_copy_copy, __uninitialized_copy_fill, __uninitialized_copy_n, __uninitialized_fill_copy, vector< node *, Alloc >::allocate_and_copy, vector< node *, Alloc >::allocate_and_fill, hashtable::copy_from, rb_tree< key_type, value_type, select1st< value_type >, key_compare, Alloc >::create_node, slist::create_node, list::create_node, deque::deque, slist::fill_initialize, list::fill_initialize, hashtable< Value, Value, HashFcn, identity< Value >, EqualKey, Alloc >::new_node, priority_queue::pop, priority_queue::push, rope::push_front, slist::range_initialize, list::range_initialize, rb_tree< key_type, value_type, select1st< value_type >, key_compare, Alloc >::rb_tree, rope::rope, rope::RopeLeaf_from_unowned_char_ptr, and temporary_buffer::temporary_buffer.

[gules]

就是异常处理。

[赵4老师]

http://www.google.com/codesearch

[daidodo]

通过宏定义，控制是否使用C++的异常机制，实现起来可能是这样：

#ifdef __STL_USE_EXCEPTIONS
#define __STL_TRY   try
#define __STL_UNWIND(action)   catch(...) { action; throw; }
#else
#define __STL_TRY
#define __STL_UNWIND(action)
#endif

[hualibinbin]

那么如果construct失败，调用put_node后是不是仍然返回p，此时p所指的内存都已经释放掉了，那p是不是NULL啊