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Re: [std-proposals] Idea of try_throw (Conditional Throw Statement)?

From: Sebastian Wittmeier <wittmeier_at_[hidden]>
Date: Mon, 29 May 2023 09:01:27 +0200
But would ignoring those 13 conditions be implementable in each case for each implementation? Can the stack be unwound in each case? To what level?   E.g. What happens, when during an exit std::atexit functions throw an exception? Is the exit stopped to 'locally' be recovered? Is the exit continued afterwards?   Would the possibility of a try throw at the caller site bloat up exception handling code in functions, where an exception with those exceptions may occur or even in all functions in between?   Perhaps you could try to write for each of the cases alternative code, which is compiled under the current rules, but has the proposed effect to show that it is implementable. E.g. if a handler is missing, insert one, etc.   You will find that in many cases  - the local handling is not the right place for handling  - the code within sub-functions cannot be made to work with and without try throw  - It will not be possible to leave some objects in a healthy/valid state, so real recovery is not possible   Probably the best you will be able to do for some of the abandoned exceptions is to exchange std::terminate with a global handler of your choosing, not for recovery, but for customized termination.   -----Ursprüngliche Nachricht----- Von:Andrew Tomazos via Std-Proposals <std-proposals_at_[hidden]> Gesendet:Mo 29.05.2023 04:16 Betreff:[std-proposals] Idea of try_throw (Conditional Throw Statement)? An:sotrdg sotrdg via Std-Proposals <std-proposals_at_[hidden]>; CC:Andrew Tomazos <andrewtomazos_at_[hidden]>; Imagine a C++ keyword `try_throw` and a try-throw-statement with the following syntax:     try-throw-statement:       try_throw assignment-expression_opt ;  If one of the 13 conditions listed in [except.terminate] (https://eel.is/c++draft/except.terminate) applies, then a try-throw-statement has no effect (and its expression is not evaluated).  Otherwise, it has the effect of a normal throw expression statement and control is passed to the appropriate catch handler.  This would mean you could write code like:      if (/* something bad */) {         /* clean up */         try_throw std::runtime_error(/*...*/);         /* attempt to recover locally */         return /* ... */;     }  In essence, it allows for falling back to local recovery when a catch handler is unavailable.   (Normally, in those situations the global terminate handler is called, and local recovery is not permitted.)  Any thoughts?   -- Std-Proposals mailing list Std-Proposals_at_[hidden] https://lists.isocpp.org/mailman/listinfo.cgi/std-proposals

Received on 2023-05-29 07:01:30