C++Talk.NET C++ language newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  questions on placement delete called after an exception.          C++Talk.NET Forum Index -> C++ language, library and standards View previous topic :: View next topic   Author Message Ganesh Guest Posted: Thu Aug 24, 2006 4:17 pm    Post subject: questions on placement delete called after an exception. Consider the following code for Dummy class where constructor of Dummy throws an exception while called with placement new: struct Dummy { Dummy() { throw -1;} }; void* operator new(size_t s, int i) { } void operator delete(void* p, int i) { if(std::uncaught_exception()) printf("an exception is active\n"); if (i == 1234) exit(0); } The constructor throws an exception while called thro placement new, corresponding placement delete is called. In that operator delete: 1) std::uncaught_exception() should return true or false? 2) what happens to the exception object as exit is called from that code? I checked [5.3.4], [3.7.3.2] and [17.4.3.4], but its not clear for me. (Sorry if I had missed anything obvious). Thanks! -Ganesh --- [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. If that fails, use mailto:std-c++@ncar.ucar.edu ] [ --- Please see the FAQ before posting. --- ] [ FAQ: http://www.comeaucomputing.com/csc/faq.html ] Back to top Shooting Guest Posted: Fri Aug 25, 2006 3:46 pm    Post subject: Re: questions on placement delete called after an exception. Ganesh wrote: Quote: Consider the following code for Dummy class where constructor of Dummy throws an exception while called with placement new: struct Dummy { Dummy() { throw -1;} }; void* operator new(size_t s, int i) { } void operator delete(void* p, int i) { if(std::uncaught_exception()) printf("an exception is active\n"); if (i == 1234) exit(0); } The constructor throws an exception while called thro placement new, corresponding placement delete is called. In that operator delete: 1) std::uncaught_exception() should return true or false? I think it should return true because there is actually a uncaught exception Quote: 2) what happens to the exception object as exit is called from that code? Destroyed I believe. Because that's the end of this process. Quote: I checked [5.3.4], [3.7.3.2] and [17.4.3.4], but its not clear for me. (Sorry if I had missed anything obvious). Thanks! -Ganesh --- [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. If that fails, use mailto:std-c++@ncar.ucar.edu ] [ --- Please see the FAQ before posting. --- ] [ FAQ: http://www.comeaucomputing.com/csc/faq.html ] --- [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. If that fails, use mailto:std-c++@ncar.ucar.edu ] [ --- Please see the FAQ before posting. --- ] [ FAQ: http://www.comeaucomputing.com/csc/faq.html ] Back to top Ganesh Guest Posted: Mon Aug 28, 2006 4:17 pm    Post subject: Re: questions on placement delete called after an exception. ===================================== MODERATOR'S COMMENT: Please don't quote moderation footers when replying. ===================================== END OF MODERATOR'S COMMENT Shooting wrote: Quote: Ganesh wrote: Consider the following code for Dummy class where constructor of Dummy throws an exception while called with placement new: struct Dummy { Dummy() { throw -1;} }; void* operator new(size_t s, int i) { } void operator delete(void* p, int i) { if(std::uncaught_exception()) printf("an exception is active\n"); if (i == 1234) exit(0); } The constructor throws an exception while called thro placement new, corresponding placement delete is called. In that operator delete: 1) std::uncaught_exception() should return true or false? I think it should return true because there is actually a uncaught exception Looks obvious, but for my surprise, compilers differ in behaviour in this. Shouldn't be that this specific case documented in the standard? Quote: 2) what happens to the exception object as exit is called from that code? Destroyed I believe. Because that's the end of this process. Compilers differ in behaviour with this too (in few compilers, it fails with uncaught exception and in a few it results in normal program termination). I think the standard should explicitly mention the behaviour. For this difference in compiler behaviours, I raised this question, for I wanted to know if its a compiler defect or defect in the standard (as it doesn't specify the behaviour in these two cases). -Ganesh Quote: I checked [5.3.4], [3.7.3.2] and [17.4.3.4], but its not clear for me. (Sorry if I had missed anything obvious). Thanks! -Ganesh --- [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. If that fails, use mailto:std-c++@ncar.ucar.edu ] [ --- Please see the FAQ before posting. --- ] [ FAQ: http://www.comeaucomputing.com/csc/faq.html ] --- [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. If that fails, use mailto:std-c++@ncar.ucar.edu ] [ --- Please see the FAQ before posting. --- ] [ FAQ: http://www.comeaucomputing.com/csc/faq.html ] --- [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. If that fails, use mailto:std-c++@ncar.ucar.edu ] [ --- Please see the FAQ before posting. --- ] [ FAQ: http://www.comeaucomputing.com/csc/faq.html ] Back to top Guest Posted: Wed Sep 06, 2006 4:14 pm    Post subject: Re: questions on placement delete called after an exception. Ganesh wrote: Quote: 1) std::uncaught_exception() should return true or false? true :) Quote: 2) what happens to the exception object as exit is called from that code? I believe that exit, after closing files and executing atexit stack, calls abort (or something equivalent), in a purist sense would't that be in violation of [3.7.3.2] ? Quote: Destroyed I believe. Because that's the end of this process. how would that be possible other than to register it's destructor with atexit --- [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. 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