boost::scope_guard lolwhat( [&](){ CloseHandle(handle); } );
... lolwhat.dismiss();
What about boost::exception_guard somename( [&](){ CloseHandle(handle); } ); that calls the function/lambda only if std::uncaught_exception() returns true?
std::uncaught_exception is very dangerous to use in this way. See
http://www.gotw.ca/gotw/047.htm This article is not about my idea. I do not propose to throw from the destructor. I propose to use uncaught_exception() to determine whether
15.09.2012 5:27, John Bytheway пишет: the resources must be freed on the scope exit or not. I propose to use the following { HANDLE h = CheckHandle( CreateFile(...) ); //CheckHandle() may throw boost::exception_guard guard( [&](){ CloseHandle(h); } ); //other code that can throw return h; //note that h must not be closed } instead of the following { bool bDontClose = false; HANDLE h = CheckHandle( CreateFile(...) ); //CheckHandle() may throw boost::scope_guard guard( [&](){ if( !bDontClose ) CloseHandle(h); } ); //other code that can throw bDontClose = true; return h; //note that h must not be closed }
In short: your function will misbehave if called from a destructor during stack unwinding. It seems strange to me. Destructors are the only places where uncaught_exception() may return true, right? What's wrong with the following?
~exception_guard() { if( uncaught_exception() ) f(); } Is it less safe than the following? ~scope_guard() { f(); } -- Best regards, Sergey Cheban