C++Talk.NET C++ language newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  The end of my streambuf road...          C++Talk.NET Forum Index -> C++ language (comp.lang.c++) View previous topic :: View next topic   Author Message Christopher Benson-Manica Guest Posted: Fri Feb 27, 2004 6:40 pm    Post subject: The end of my streambuf road... Unless there is something wrong with the following complete C++ file, I think my quest to stream-ize our code will be at an end :( #include <sstream> #include <iostream> using namespace std; class linebuf : public streambuf { protected: string buffer; public: virtual char overflow(char c) {if(c!=EOF) buffer+=c; return c;} virtual streamsize xsputn(const char *s, streamsize num) { buffer.append(s,num); return num; } virtual int sync()=0; }; typedef unsigned int uint; typedef bool (* FTYPE)(const void *,uint,uint,uint); class sendbuf : public linebuf { public: virtual int sync() {cout << buffer << endl; buffer.erase(); return 0;} }; class mystream : public std::ostream { protected: sendbuf buf; public: mystream() : std::ostream(&buf) {} }; int main(void) { mystream s; s << "Hello, " << "world!" << flush; return 0; } g++, faithful and true companion that it is, compiles and runs this as expected with all warnings enabled. Our Borland setup, however, compiles this into an executable that crashes. So I figure either I'm invoking some wicked implementation-defined (or undefined!) behavior here, or our Borland setup is fatally flawed in ways that I cannot begin to fathom. Thanks to everyone who provided assistance during my travails - it was a great learning experience if nothing else! -- Christopher Benson-Manica | I *should* know what I'm talking about - if I ataru(at)cyberspace.org | don't, I need to know. Flames welcome. Back to top Leor Zolman Guest Posted: Fri Feb 27, 2004 6:47 pm    Post subject: Re: The end of my streambuf road... On Fri, 27 Feb 2004 18:40:03 +0000 (UTC), Christopher Benson-Manica <ataru (AT) nospam (DOT) cyberspace.org> wrote: Quote: Unless there is something wrong with the following complete C++ file, I think my quest to stream-ize our code will be at an end :( #include <sstream #include using namespace std; class linebuf : public streambuf { protected: string buffer; public: virtual char overflow(char c) {if(c!=EOF) buffer+=c; return c;} virtual streamsize xsputn(const char *s, streamsize num) { buffer.append(s,num); return num; } virtual int sync()=0; }; typedef unsigned int uint; typedef bool (* FTYPE)(const void *,uint,uint,uint); class sendbuf : public linebuf { public: virtual int sync() {cout << buffer << endl; buffer.erase(); return 0;} }; class mystream : public std::ostream { protected: sendbuf buf; public: mystream() : std::ostream(&buf) {} }; int main(void) { mystream s; s << "Hello, " << "world!" << flush; return 0; } g++, faithful and true companion that it is, compiles and runs this as expected with all warnings enabled. Our Borland setup, however, compiles this into an executable that crashes. So I figure either I'm invoking some wicked implementation-defined (or undefined!) behavior here, or our Borland setup is fatally flawed in ways that I cannot begin to fathom. Thanks to everyone who provided assistance during my travails - it was a great learning experience if nothing else! Here's what Comeau says: stream.cpp(13): warning: function "basic_streambuf char_traits::overflow( basic_streambuf<char, char_traits::int_type)" is hidden by "linebuf::overflow" -- virtual function override intended? virtual char overflow(char c) {if(c!=EOF) buffer+=c; return c;} ^ (the caret is pointing at the start of the word "overflowa" in the last line). Any help? -leor Leor Zolman BD Software [email]leor (AT) bdsoft (DOT) com[/email] www.bdsoft.com -- On-Site Training in C/C++, Java, Perl & Unix C++ users: Download BD Software's free STL Error Message Decryptor at www.bdsoft.com/tools/stlfilt.html Back to top Christopher Benson-Manica Guest Posted: Fri Feb 27, 2004 6:55 pm    Post subject: Re: The end of my streambuf road... Leor Zolman <leor (AT) bdsoft (DOT) com> spoke thus: Quote: stream.cpp(13): warning: function "basic_streambuf<char, char_traits::overflow( basic_streambuf<char, char_traits::int_type)" is hidden by "linebuf::overflow" -- virtual function override intended? virtual char overflow(char c) {if(c!=EOF) buffer+=c; return c;} ^ (the caret is pointing at the start of the word "overflowa" in the last line). Any help? It is int_type in the code compiled by Borland - I changed it because g++ complained... -- Christopher Benson-Manica | I *should* know what I'm talking about - if I ataru(at)cyberspace.org | don't, I need to know. Flames welcome. Back to top Dietmar Kuehl Guest Posted: Sat Feb 28, 2004 3:39 am    Post subject: Re: The end of my streambuf road... Christopher Benson-Manica wrote: Quote: class linebuf : public streambuf { protected: string buffer; There is no point in making member variables protected: you could as well make them public they become part of your interface anyway (well, given that the size changes with a type change, in some sense even private variables are part of the interface...). However, this is not really your problem... Quote: public: virtual char overflow(char c) {if(c!=EOF) buffer+=c; return c;} This is not an override but an overload! You should use 'int_type' or, if this causes problems, 'std::char_traits<char>::int_type'. Using 'char' will definitely cause problems. The 'overflow()' function would look something like this: int_type overflow(int_type c) { if (!traits::eq_int_type(c, traits::eof())) buffer += traits::to_char_type(c); return traits::not_eof(c); } -- <mailto:dietmar_kuehl (AT) yahoo (DOT) com> <http://www.dietmar-kuehl.de/> Phaidros eaSE - Easy Software Engineering: <http://www.phaidros.com/> 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.