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This article mainly introduces "what does the failure of destructors in C++ explain". In daily operation, I believe that many people have doubts about what the failure of destructors means in C++. I have consulted all kinds of materials and sorted out simple and easy-to-use methods of operation. I hope it will be helpful for you to answer the doubts of "what does the failure of destructors in C++ mean?" Next, please follow the editor to study!

Destructors should not fail Reason (reason)

If the destructor fails, we usually don't know how to write error-free code. The standard library requires it to handle all class destructors without throwing exceptions.

Example (sample)

Class X {

Public:

~ X () noexcept

/ /...

}

XRV () noexcept {

/ /...

If (cannot_release_a_resource) terminate ()

/ /...

}

Note (Note)

Various attempts have been made to invent reliable ways to deal with errors in destructors. No method has developed into a general practice. This is a real practical question: for example, what if socket cannot be shut down? The writer of the destructor does not know why the destructor is called and cannot reject this action by throwing an exception. To make matters worse, many "close / release" operations cannot be retried. If possible, treat the error that occurred during the shutdown / release as a basic design error and terminate the execution.

Note (Note)

Define the destructor as noexcept. This will ensure that either the destructor ends normally or the program is terminated.

Note (Note)

If resources cannot be released and the program may not fail, error signals are sent to other parts of the program in some way (or even by modifying some global variables and hoping that some programs will notice and deal with the problem). You need to be fully aware of the special purpose of this technology and are prone to errors. Consider the example "my link will not be closed". It is possible that there is a problem at the other end of the connection, and there is only one piece of code responsible for handling the problem correctly on both ends of the link. The destructor can (in some way) send a message to the part of the system responsible for handling the error, while assuming that we have closed the link and returned correctly.

Note (Note)

If the destructor uses operations that may fail, it can catch the exception itself and still end successfully in some cases (for example, using a different cleanup mechanism other than throwing the exception).

Enforcement (implementation recommendations)

(simple) if it is possible to throw an exception, the destructor should be declared noexcept.

Translator's note: by declaring noexcept, the compiler will not generate an exception delivery mechanism, and once an exception is thrown, the program will be aborted directly.

At this point, the study of "what does the failure of destructors in C++ mean?" is over. I hope I can solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

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