C++Talk.NET C++ language newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  unexpected shame^w exception Goto page 1, 2  Next          C++Talk.NET Forum Index -> C++ Language (Moderated) View previous topic :: View next topic   Author Message news@pgxml.net Guest Posted: Thu Oct 14, 2004 10:00 pm    Post subject: unexpected shame^w exception Hi! As the subject hints i recently had to deal with an unexpected exception. Context in short (one of the calling methods promised to throw only runtime_error): enum Blah { ja,nein,mir_egal } blah; inline SomeStream& operator >> ( SomeStream& stream, Blah& myBlah ) { unsigned int tmp; stream >> tmp; myBlah = static_cast< Blah >( tmp ); return stream; } Do not ask, i know myself its not a good idea to code java and c++ in parallel. ;-) So my "masterpiece" terminated with a SIGABRT (linux-box), leaving me with ??? in my eyes staring a the core dump. In this case a "-fno-enforce-eh-specs" in the g++ flags helped me to find out that there was a bad_cast in play, but that cant be it. if i set a handler via set_unexpected( some_handler ), the handler only gets the information that there *was* a unexpected exception, but not from where and which one, right? I fear its getting compiler-specific, but are there any more or less "standard-compliant" ways to get more information about the evil-doer[1]? Dirty fantasies or just URIs are welcome. cu! christoph Footnotes: [1] except the PEBKAC? -- sig? *sigh* [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Alberto Barbati Guest Posted: Fri Oct 15, 2004 11:30 am    Post subject: Re: unexpected shame^w exception [email]news (AT) pgxml (DOT) net[/email] wrote: Quote: Hi! As the subject hints i recently had to deal with an unexpected exception. Context in short (one of the calling methods promised to throw only runtime_error): enum Blah { ja,nein,mir_egal } blah; inline SomeStream& operator >> ( SomeStream& stream, Blah& myBlah ) { unsigned int tmp; stream >> tmp; myBlah = static_cast< Blah >( tmp ); return stream; } I think you got the context a bit too short... What's SomeStream? I assume SomeStream is a standard istream. Quote: Do not ask, i know myself its not a good idea to code java and c++ in parallel. I won't ask. Why should I? Quote: In this case a "-fno-enforce-eh-specs" in the g++ flags helped me to find out that there was a bad_cast in play, but that cant be it. A bad_cast? That's an interesting piece of info. It *can* be it, indeed. One thing that might throw a bad_cast in the code above is the access to the stream's locale facet num_get. Either: 1) you messed up with the stream's locale 2) SomeStream is (or is derived from) basic_istream<> with a char_type which is not either char or wchar_t Quote: if i set a handler via set_unexpected( some_handler ), the handler only gets the information that there *was* a unexpected exception, but not from where and which one, right? Right, set_unexpected won't help you very much. Quote: I fear its getting compiler-specific, but are there any more or less "standard-compliant" ways to get more information about the evil-doer[1]? Dirty fantasies or just URIs are welcome. Usually executing the code in a debugger is the easiest way. Most (if not all) modern debuggers allow you to break execution just before an exception is thrown. HTH, Alberto [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Vitaly Repin Guest Posted: Fri Oct 15, 2004 9:56 pm    Post subject: Re: unexpected shame^w exception Hello! Yes, I can introduce one "standard-compliant" way to get some information of the exception: void log_exception_info() throw() { try { throw; } catch (std::exception& e) { logg(Lvl_error, "Exception what() = %s", prefix, e.what()); logg(Lvl_error, "exception RTTI: %s", prefix, typeid(e).name()); } catch (...) { logg(Lvl_error, "There is no information about that exception, sorry"); } }; You simply re-generate the last exception. If unexpected exception was derived from std::exception, it's virtual member function what() is executed. Otherwise, only non-meaningful message is printed. That's whay I prefer to derive my exceptions from one base class, std::exception. [email]news (AT) pgxml (DOT) net[/email] wrote in message news:<87655dvzsc.fsf (AT) gandalf (DOT) pgxml.net>... Quote: if i set a handler via set_unexpected( some_handler ), the handler only gets the information that there *was* a unexpected exception, but not from where and which one, right? I fear its getting compiler-specific, but are there any more or less "standard-compliant" ways to get more information about the evil-doer[1]? Dirty fantasies or just URIs are welcome. Good bye! -- WBR & WBW, Vitaly [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Michael Karcher Guest Posted: Fri Oct 15, 2004 10:50 pm    Post subject: Re: unexpected shame^w exception Alberto Barbati <AlbertoBarbati (AT) libero (DOT) it> wrote: Quote: Usually executing the code in a debugger is the easiest way. Most (if not all) modern debuggers allow you to break execution just before an exception is thrown. JFTR, as gcc was mentioned: gdb 6.1 on i386 (at least on my debian box) says "sorry, not implemented" on "catch throw", but it works to set a breakpoint on __cxa_throw. Michael Karcher [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top John Torjo Guest Posted: Fri Oct 15, 2004 11:21 pm    Post subject: Re: unexpected shame^w exception [email]news (AT) pgxml (DOT) net[/email] wrote in message news:<87655dvzsc.fsf (AT) gandalf (DOT) pgxml.net>... Quote: Hi! As the subject hints i recently had to deal with an unexpected exception. Context in short (one of the calling methods promised to throw only runtime_error): [...] I really don't think you've provided us with enough information to do any judgement. Could you be a little more specific? Best, John John Torjo, Contributing editor, C/C++ Users Journal -- "Win32 GUI Generics" -- generics & GUI do mix, after all -- http://www.torjo.com/win32gui/ -- v1.5 - tooltips at your fingertips (work for menus too!) + bitmap buttons, tab dialogs, hyper links, lite html [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top news@pgxml.net Guest Posted: Sun Oct 17, 2004 1:40 am    Post subject: Re: unexpected shame^w exception [email]jtorjo (AT) yahoo (DOT) com[/email] (John Torjo) writes: Quote: news (AT) pgxml (DOT) net wrote in message news:<87655dvzsc.fsf (AT) gandalf (DOT) pgxml.net>... Hi! As the subject hints i recently had to deal with an unexpected exception. Context in short (one of the calling methods promised to throw only runtime_error): [...] I really don't think you've provided us with enough information to do any judgement. Could you be a little more specific? Hm.. no. I think it should be less specific. The problem is not that stream that threw that exception (code that i will throw away anyway), i am looking for means to deal with unexpected exceptions. Just terminate a program without any information why cant be it. What if you linked against a third party lib that throws something unkown? cu! christoph [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top news@pgxml.net Guest Posted: Sun Oct 17, 2004 1:41 am    Post subject: Re: unexpected shame^w exception [email]programm (AT) metrocom (DOT) ru[/email] (Vitaly Repin) writes: Quote: Hello! Yes, I can introduce one "standard-compliant" way to get some information of the exception: void log_exception_info() throw() { try { throw; } catch (std::exception& e) { logg(Lvl_error, "Exception what() = %s", prefix, e.what()); logg(Lvl_error, "exception RTTI: %s", prefix, typeid(e).name()); } catch (...) { logg(Lvl_error, "There is no information about that exception, } sorry"); } }; You simply re-generate the last exception. I am not sure if i understand correctly: this is the handler set via set_unexcpected? cu! christoph [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Vitaly Repin Guest Posted: Mon Oct 18, 2004 5:27 pm    Post subject: Re: unexpected shame^w exception Hello! [email]news (AT) pgxml (DOT) net[/email] wrote in message news:<87zn2m1qro.fsf (AT) gandalf (DOT) pgxml.net>... Quote: You simply re-generate the last exception. I am not sure if i understand correctly: this is the handler set via set_unexcpected? This function can be executed from the handler of unexpected exceptions. Good bye! -- WBR & WBW, Vitaly [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top John Torjo Guest Posted: Mon Oct 18, 2004 7:03 pm    Post subject: Re: unexpected shame^w exception Quote: I really don't think you've provided us with enough information to do any judgement. Could you be a little more specific? Hm.. no. I think it should be less specific. The problem is not that stream that threw that exception (code that i will throw away anyway), i am looking for means to deal with unexpected exceptions. Just terminate a program without any information why cant be it. What if you linked against a third party lib that throws something unkown? If it's unexpected, how can you deal with it ? Now seriously, IMO a well-behaved exception class should derive from std::exception. Thus, you can catch std::exception, and at least report the .what() string. And catch(...), and report something like "unexpected exception". Best, John John Torjo, Contributing editor, C/C++ Users Journal -- "Win32 GUI Generics" -- generics & GUI do mix, after all -- http://www.torjo.com/win32gui/ -- v1.5 - tooltips at your fingertips (work for menus too!) + bitmap buttons, tab dialogs, hyper links, lite html [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top kanze@gabi-soft.fr Guest Posted: Tue Oct 19, 2004 5:58 pm    Post subject: Re: unexpected shame^w exception [email]jtorjo (AT) yahoo (DOT) com[/email] (John Torjo) wrote in message news:<c638aac5.0410180932.1e213580 (AT) posting (DOT) google.com>... Quote: I really don't think you've provided us with enough information to do any judgement. Could you be a little more specific? Hm.. no. I think it should be less specific. The problem is not that stream that threw that exception (code that i will throw away anyway), i am looking for means to deal with unexpected exceptions. Just terminate a program without any information why cant be it. What if you linked against a third party lib that throws something unkown? If it's unexpected, how can you deal with it ? Now seriously, IMO a well-behaved exception class should derive from std::exception. Thus, you can catch std::exception, and at least report the .what() string. I'd also output something like typeid( exception ).name(). Quote: And catch(...), and report something like "unexpected exception". It's rather a shame that you can't at least find out the type, given that the system must know it. -- James Kanze GABI Software http://www.gabi-soft.fr Conseils en informatique orientée objet/ Beratung in objektorientierter Datenverarbeitung 9 place Sémard, 78210 St.-Cyr-l'École, France, +33 (0)1 30 23 00 34 [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top news@pgxml.net Guest Posted: Wed Oct 20, 2004 6:34 pm    Post subject: Re: unexpected shame^w exception Hi! I mix two answers in this posting. ;-) [email]kanze (AT) gabi-soft (DOT) fr[/email] writes: Quote: jtorjo (AT) yahoo (DOT) com (John Torjo) wrote in message [...] Quote: Hm.. no. I think it should be less specific. The problem is not that stream that threw that exception (code that i will throw away anyway), i am looking for means to deal with unexpected exceptions. Just terminate a program without any information why cant be it. What if you linked against a third party lib that throws something unkown? [...] Quote: Now seriously, IMO a well-behaved exception class should derive from std::exception. Thus, you can catch std::exception, and at least report the .what() string. Yes... but: in case of doubt the information reported by what() has a value close to zero[1]. Quote: I'd also output something like typeid( exception ).name(). Yes.. neat... nice. But this is not the way to enlightenment in the end. (in my very humble opinion) Quote: And catch(...), and report something like "unexpected exception". It's rather a shame that you can't at least find out the type, given that the system must know it. Yepp. So now, "bring out the dead" and let us see what can be done at least to the stuff that is compiled on our own machines. I think of [2] having std::exception inherit a class that can tell from where the exception comes (compilation unit, method/function, linenumber)... hm... iam not the first one who has dark thoughts like these? [x] <-- fill in your input here. cu, christoph Footnotes: [1] i am no native english speaker; in german it would be "der Informationsgehalt geht gegen Null" [2] yes.. drity.. depends on the compiler... violates standard.. i know. [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top John Torjo Guest Posted: Wed Oct 20, 2004 9:38 pm    Post subject: Re: unexpected shame^w exception Quote: I'd also output something like typeid( exception ).name(). True. That's a bliss with VC71. A less of a bliss with gcc, however... Quote: And catch(...), and report something like "unexpected exception". It's rather a shame that you can't at least find out the type, given that the system must know it. True... It would be great if the compiler would do us a favor, and wrap it up as a C++ std::exception derived exception ;) Best, John John Torjo, Contributing editor, C/C++ Users Journal -- "Win32 GUI Generics" -- generics & GUI do mix, after all -- http://www.torjo.com/win32gui/ -- v1.5 - tooltips at your fingertips (work for menus too!) + bitmap buttons, tab dialogs, hyper links, lite html [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Alberto Barbati Guest Posted: Thu Oct 21, 2004 5:14 pm    Post subject: Re: unexpected shame^w exception [email]kanze (AT) gabi-soft (DOT) fr[/email] wrote: Quote: And catch(...), and report something like "unexpected exception". It's rather a shame that you can't at least find out the type, given that the system must know it. It would be nice to have: catch(auto& e) { //... } isn't it? ;-) Alberto [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top kanze@gabi-soft.fr Guest Posted: Thu Oct 21, 2004 5:31 pm    Post subject: Re: unexpected shame^w exception [email]jtorjo (AT) yahoo (DOT) com[/email] (John Torjo) wrote in message news:<c638aac5.0410192321.6490cdd7 (AT) posting (DOT) google.com>... Quote: I'd also output something like typeid( exception ).name(). True. That's a bliss with VC71. A less of a bliss with gcc, however... I've not tried it with VC++, but from what I've seen, g++ seems to be amongst the worse here. Even Sun CC is better. Quote: And catch(...), and report something like "unexpected exception". It's rather a shame that you can't at least find out the type, given that the system must know it. True... It would be great if the compiler would do us a favor, and wrap it up as a C++ std::exception derived exception I'm not really that much in favor of wrapping, although I suppose with a templated derived type, it would be a solution. But what I was really thinking of was something much simpler, along the lines, say, of a standard function: typeid const& get_current_exception() ; I'm pretty sure that the implementation must have this information at hand, otherwise, how could throw (without an argument) work? -- James Kanze GABI Software http://www.gabi-soft.fr Conseils en informatique orientée objet/ Beratung in objektorientierter Datenverarbeitung 9 place Sémard, 78210 St.-Cyr-l'École, France, +33 (0)1 30 23 00 34 [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Frank Birbacher Guest Posted: Sun Oct 24, 2004 2:45 pm    Post subject: Re: unexpected shame^w exception Hi! Alberto Barbati wrote: Quote: It would be nice to have: catch(auto& e) { //... } isn't it? or maybe: try{ //... } template<typename T> catch(T& e) { //access typeid(T) } ;) and maybe specialize it Frank [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. 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