Hello Ilya, Friday, August 24, 2007, 3:10:57 PM, you wrote:
Andrey Semashev wrote:
Consider the following examples:
Example 1:
void foo(std::set< int >& my_set) { bool commit = false; std::set< int >::iterator it = my_set.insert(10); BOOST_SCOPE_EXIT((my_set)(it)(commit)) { // Which one will be erased here? // Not necessarily the one we intended to.
Sorry for such late response. Can you explain what is intended value of it?
The scope exit block is supposed to undo the insertion into the my_set. So the intended value is the value returned from "insert".
Example 2:
class A { int m_i;
void foo() { m_i = 1; BOOST_SCOPE_EXIT((m_i)) { // What's the value of m_i here? std::cout << m_i << std::endl; } BOOST_SCOPE_EXIT_END
bar(); }
I believe BOOST_SCOPE_EXIT should be moved to the end of foo(). I am thinking about BOOST_SCOPE_EXIT as of try/finally with different layout of braces:
No, you missed the point. The bar function may throw, and the scope exit block is there just for that reason - this block should be executed regardless from the way of returning from foo. As for "finally" analogy, while BOOST_SCOPE_EXIT does the same thing, it has no such drawback like the need to be written somewhere in the end of the function. It may be declared right below the code it is intended to complement. This is noted in the library docs. -- Best regards, Andrey mailto:andysem@mail.ru