C++Talk.NET C++ language newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Calling builtin new          C++Talk.NET Forum Index -> C++ language (comp.lang.c++) View previous topic :: View next topic   Author Message Shayne Wissler Guest Posted: Fri Jan 30, 2004 8:05 pm    Post subject: Calling builtin new I've overloaded the global new operator, so that I can, detect when I've run out of memory: extern void* operator new(size_t s) { void *r = malloc(s); if (!r && s) { fprintf(stderr, "Error: No more memory."); exit(1); } return r; } The problem here is that I don't really want to call malloc (and--Valgrind is quite noisy about me doing this); I want to call the implementation of new that I overrode. Suggestions? Thanks, Shayne Wissler Back to top Le Géant Vert Guest Posted: Fri Jan 30, 2004 8:21 pm    Post subject: Re: Calling builtin new Shayne Wissler wrote: Quote: I've overloaded the global new operator, so that I can, detect when I've run out of memory: extern void* operator new(size_t s) { void *r = malloc(s); if (!r && s) { fprintf(stderr, "Error: No more memory."); exit(1); } return r; } The problem here is that I don't really want to call malloc (and--Valgrind is quite noisy about me doing this); I want to call the implementation of new that I overrode. Suggestions? Thanks, Shayne Wissler I've done quite the same thing to detect memory leaks due to mismatching new/delete ; what I've done overload operator new with some more parameters : the size, the filename of the source, and the line (to display where memory leak occurs). if you do as I've done (to display where "out of memory" occurs for example), you'll have something like : void *operator new(size_t, char *, unsigned long); and you won't have any problem calling the original ::operator new(size_t) .... my solution... if anyone has a better idea... Back to top Thomas Matthews Guest Posted: Fri Jan 30, 2004 9:50 pm    Post subject: Re: Calling builtin new Shayne Wissler wrote: Quote: I've overloaded the global new operator, so that I can, detect when I've run out of memory: My understanding is that the "new" operator throws an exception when there are memory problems. Perhaps you could catch the exception to detect when you've run out of memory. Quote: extern void* operator new(size_t s) { void *r = malloc(s); if (!r && s) { fprintf(stderr, "Error: No more memory."); exit(1); } return r; } The problem here is that I don't really want to call malloc (and--Valgrind is quite noisy about me doing this); I want to call the implementation of new that I overrode. Suggestions? Here I don't understand. If you overload the global new operator, then have your function call the global new operator, isn't this called recursion (or perhaps an infinite loop)? Quote: Thanks, Shayne Wissler -- Thomas Matthews C++ newsgroup welcome message: http://www.slack.net/~shiva/welcome.txt C++ Faq: http://www.parashift.com/c++-faq-lite C Faq: http://www.eskimo.com/~scs/c-faq/top.html alt.comp.lang.learn.c-c++ faq: http://www.raos.demon.uk/acllc-c++/faq.html Other sites: http://www.josuttis.com -- C++ STL Library book Back to top Shayne Wissler Guest Posted: Fri Jan 30, 2004 10:27 pm    Post subject: Re: Calling builtin new "Thomas Matthews" <Thomas_MatthewsSpitsOnSpamBots (AT) sbcglobal (DOT) net> wrote in message news:RkASb.13798$fH5.5665 (AT) newssvr16 (DOT) news.prodigy.com... Quote: Shayne Wissler wrote: I've overloaded the global new operator, so that I can, detect when I've run out of memory: My understanding is that the "new" operator throws an exception when there are memory problems. Perhaps you could catch the exception to detect when you've run out of memory. It does indeed, thanks. However, I caught with catch(...) when I tested this, is there a standard exception I should be catching instead of this catch-all? Quote: The problem here is that I don't really want to call malloc (and--Valgrind is quite noisy about me doing this); I want to call the implementation of new that I overrode. Suggestions? Here I don't understand. If you overload the global new operator, then have your function call the global new operator, isn't this called recursion (or perhaps an infinite loop)? What I meant was that I want to call the builtin-new, the one I had overridden. Just like when I override a virtual method, I can still call the base class's version of that method. How do I refer to the "base" version of the new operator? Shayne Wissler Back to top Rolf Magnus Guest Posted: Fri Jan 30, 2004 10:39 pm    Post subject: Re: Calling builtin new Shayne Wissler wrote: Quote: "Thomas Matthews" <Thomas_MatthewsSpitsOnSpamBots (AT) sbcglobal (DOT) net> wrote in message news:RkASb.13798$fH5.5665 (AT) newssvr16 (DOT) news.prodigy.com... Shayne Wissler wrote: I've overloaded the global new operator, so that I can, detect when I've run out of memory: My understanding is that the "new" operator throws an exception when there are memory problems. Perhaps you could catch the exception to detect when you've run out of memory. It does indeed, thanks. However, I caught with catch(...) when I tested this, is there a standard exception I should be catching instead of this catch-all? yes, std::bad_alloc. Quote: The problem here is that I don't really want to call malloc (and--Valgrind is quite noisy about me doing this); I want to call the implementation of new that I overrode. Suggestions? Here I don't understand. If you overload the global new operator, then have your function call the global new operator, isn't this called recursion (or perhaps an infinite loop)? What I meant was that I want to call the builtin-new, the one I had overridden. Just like when I override a virtual method, I can still call the base class's version of that method. That's a member of another class though. Quote: How do I refer to the "base" version of the new operator? I don't know if that's possible at all. Back to top Shayne Wissler Guest Posted: Fri Jan 30, 2004 11:05 pm    Post subject: Re: Calling builtin new "Rolf Magnus" <ramagnus (AT) t-online (DOT) de> wrote Quote: It does indeed, thanks. However, I caught with catch(...) when I tested this, is there a standard exception I should be catching instead of this catch-all? yes, std::bad_alloc. Thanks. Quote: Here I don't understand. If you overload the global new operator, then have your function call the global new operator, isn't this called recursion (or perhaps an infinite loop)? What I meant was that I want to call the builtin-new, the one I had overridden. Just like when I override a virtual method, I can still call the base class's version of that method. That's a member of another class though. The principle is the same. Quote: How do I refer to the "base" version of the new operator? I don't know if that's possible at all. One ought to be able to do such a thing. Shayne Wissler Back to top Rolf Magnus Guest Posted: Fri Jan 30, 2004 11:26 pm    Post subject: Re: Calling builtin new Shayne Wissler wrote: Quote: Here I don't understand. If you overload the global new operator, then have your function call the global new operator, isn't this called recursion (or perhaps an infinite loop)? What I meant was that I want to call the builtin-new, the one I had overridden. Just like when I override a virtual method, I can still call the base class's version of that method. That's a member of another class though. The principle is the same. Not really. You want to call a built-in function from a user-defined function that replaces it, which is very different from the overloading example, where you just call a user-defined fuction from another user-defined function. Other example: If you implement your own operator=(), how would you call the builtin operator=() for the same class from that? I'd assume there is none in this case (after all - you replaced it), so it can't be called. Quote: How do I refer to the "base" version of the new operator? I don't know if that's possible at all. One ought to be able to do such a thing. As I said, I don't know. Back to top lilburne Guest Posted: Fri Jan 30, 2004 11:31 pm    Post subject: Re: Calling builtin new Thomas Matthews wrote: Quote: Shayne Wissler wrote: I've overloaded the global new operator, so that I can, detect when I've run out of memory: My understanding is that the "new" operator throws an exception when there are memory problems. Perhaps you could catch the exception to detect when you've run out of memory. Why not simply do a: void myFunctionToCallWhenOutOfMemory(); set_new_handler(myFunctionToCallWhenOutOfMemory); Section 18.4.2.2 and 18.4.2.3. Then you get to find out when memory is exhausted, before exceptions are thrown, and have the opportunity to free up some memory (page out to secondary storage). If a handler is set two attempts are made to obtain memory the exception is only thrown if the second attempt fails. Back to top Shayne Wissler Guest Posted: Sat Jan 31, 2004 12:13 am    Post subject: Re: Calling builtin new "Rolf Magnus" <ramagnus (AT) t-online (DOT) de> wrote Quote: Shayne Wissler wrote: Here I don't understand. If you overload the global new operator, then have your function call the global new operator, isn't this called recursion (or perhaps an infinite loop)? What I meant was that I want to call the builtin-new, the one I had overridden. Just like when I override a virtual method, I can still call the base class's version of that method. That's a member of another class though. The principle is the same. Not really. You want to call a built-in function from a user-defined function that replaces it, which is very different from the overloading example, where you just call a user-defined fuction from another user-defined function. I said the principle was the same, not the scenario. Shayne Wissler Back to top Rolf Magnus Guest Posted: Sat Jan 31, 2004 11:35 am    Post subject: Re: Calling builtin new Shayne Wissler wrote: Quote: "Rolf Magnus" <ramagnus (AT) t-online (DOT) de> wrote in message news:bvepo6$vug$04$1 (AT) news (DOT) t-online.com... Shayne Wissler wrote: Here I don't understand. If you overload the global new operator, then have your function call the global new operator, isn't this called recursion (or perhaps an infinite loop)? What I meant was that I want to call the builtin-new, the one I had overridden. Just like when I override a virtual method, I can still call the base class's version of that method. That's a member of another class though. The principle is the same. Not really. You want to call a built-in function from a user-defined function that replaces it, which is very different from the overloading example, where you just call a user-defined fuction from another user-defined function. I said the principle was the same, not the scenario. And my point is that the principle is not at all the same. One is simple calling a regular function, the other one is calling a built-in that was replaced. Back to top Jerry Coffin Guest Posted: Sat Feb 14, 2004 6:57 am    Post subject: Re: Calling builtin new In article <DOySb.59476$U%5.345456@attbi_s03>, [email]thalesNOSPAM000 (AT) yahoo (DOT) com[/email] says... Quote: I've overloaded the global new operator, so that I can, detect when I've run out of memory: There's no need to overload operator new to handle this -- the library provides set_new_handler for precisely this purpose. Quote: The problem here is that I don't really want to call malloc (and--Valgrind is quite noisy about me doing this); I want to call the implementation of new that I overrode. Suggestions? Yes: don't even try this -- it's doomed from the beginning. From the viewpoint of the compiler, you've overridden a function which is fine and well. From the viewpoint of the linker (at least on the typical implementations that use linkers) this operator satisfies all external references in the program to the symbol with whatever name global operator new mangles to with your compiler. Since the references to the name have been satisfied, the linker will NOT include the one that's in the standard library. IOW, you can't call it because in your program it doesn't even exist. -- Later, Jerry. The universe is a figment of its own imagination. Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         C++Talk.NET Forum Index -> C++ language (comp.lang.c++) All times are GMT Page 1 of 1   Jump to: Select a forum C/C++----------------C LanguageC Language (Moderated)C++ Language (Moderated)C++ language (comp.lang.c++)C++ language, library and standards Non-English C/C++ Newsgroups----------------C++ (German)C++ (French)  You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum Powered by phpBB © 2001, 2006 phpBB Group SEO toolkit © 2004-2006 webmedic.