Also note that destructors of temporary objects are scheduled to be run after the full expression they were created in is executed. This might create surprising effects. Consider the following code. Even though the assertion evaluates to true at compile-time, the expression below may still throw an exception at run-time; because the expression creates three temporaries, execution of destructors of those temporaries is not checked in the assertion, and any of these destructors could throw unless they are declared as noexcept.
In order to prevent that, you need to either explicitly declare your destructor as noexcept false or derive from a user-defined type with noexcept false -destructor or have a non-static data member of user-defined type with noexcept false -destructor. This means that if you used to throw from destructors inadvertently, you will be now calling std::terminate inadvertently. Throw from destructor inadvertently?
Do you use a log in your application? Do you log destruction of objects, like this? Even if your logging library swallows all failures logging may fail after all , does LOG take its arguments by value or by reference?
A Reference to type std::string? If you log, do you try to wrap the logging with a catch-all handler that will swallow an exception? This is the case for std::thread. If you create an automatic object of class std::thread in order to launch an asynchronous computation, and you leave the scope trigger the destructor call without having joined with or detached from the other thread, std::terminate will be called.
Note that even if your intention is to join with the other thread it might be prevented by an exception throw. Therefore, the advice for you regarding threads is, do not use such low-level abstraction as thread — really.
Use std::async instead:. Excellent post! Thank you! The section Function-try-blocks is not completely true. Indeed, and now I also noticed that at the time of reaching the handler, the member sub-objects have definitely been destroyed. Thanks for pointing this out! Interesting morning reading. Thus stack allocated objects can still throw from their destructors dribeas wrote above about consequences.
Hi Dimitry. The Standard also defines a similar requirement for destructors, although in a two-step manner:. An implicitly declared special member function shall have an exception-specification.
A declaration of a destructor that does not have an exception-specification is implicitly considered to have the same exception-specification as an implicit declaration. Pingback: Missing destructor in Visual Studio? You are commenting using your WordPress. You are commenting using your Google account.
You are commenting using your Twitter account. You are commenting using your Facebook account. Notify me of new comments via email. Notify me of new posts via email. This site uses Akismet to reduce spam. This is called stack unwinding. During stack unwinding, all the local objects in all those stack frames are destructed. There is no good answer — either choice loses information. Bang you're dead. The easy way to prevent this is never throw an exception from a destructor. But if you really want to be clever, you can say never throw an exception from a destructor while processing another exception.
But in this second case, you're in a difficult situation: the destructor itself needs code to handle both throwing an exception and doing "something else", and the caller has no guarantees as to what might happen when the destructor detects an error it might throw an exception, it might do "something else".
So the whole solution is harder to write. So the easy thing to do is always do "something else". If the stream is configured to throw exceptions on error, those exceptions are swallowed by the destructor. Health Factor Efficiency. It's built on thousands of analyzed applications, made of 35 different technologies, by over business organizations across major verticals. It provides IT Leaders with factual key analytics to let them know if their applications are on track.
Benchmark Statistics. Global Compliance.
0コメント