C++ proper cleanup redirected buffer for tee ostream
Question
I need to output messages to both console and log files. After googling, i learnt "teebuf" concept which basically create a custom class inherited from basic_streambuf. This work fine but how to clean up the redirected buffer properly. I mean how to implement RAII for "tee" buffer so i don't need to bother it every time when i need to quit the program.
Remark: currently using boost library is not a option for me.
Code Segment
int main() {
std::streambuf* cout_sbuf = std::cout.rdbuf();
std::ofstream fout(fileOutDebug);
teeoutbuf teeout(std::cout.rdbuf(), fout.rdbuf());
std::cout.rdbuf(&teeout);
// some code ...
if (failed) {
std::cout.rdbuf(cout_sbuf); // <-- i once comment this and it gives error
return -1;
}
// some more code ...
std::cout.rdbuf(cout_sbuf); // <-- i once comment this and it gives error
return 0;
}
Code Segment (My trial implementation, but fail)
template < typename CharT, typename Traits = std::char_traits<CharT>
> class basic_tostream : std::basic_ostream<CharT, Traits>
{
public:
basic_tostream(std::basic_ostream<CharT, Traits> & o1,
std::basic_ostream<CharT, Traits> & o2)
: std::basic_ostream<CharT, Traits>(&tbuf),
tbuf(o1.rdbuf(), o2.rdbuf()) {}
void print(char* msg);
private:
basic_teebuf<CharT, Traits> tbuf; // internal buffer (tee-version)
};
typedef basic_tostream<char> tostream;
int main() {
std::ofstream fout(fileOutDebug);
tostream tee(std::cout, fout, verbose);
tee << "test 1\n"; // <-- compile error
tee.print("sometext"); // <-- comment above and it run fine, both file and console written
}
Error message: 'std::basic_ostream' is an inaccessible base of 'basic_tostream'
Solution
You should use:
template < typename CharT, typename Traits = std::char_traits<CharT> >
class basic_tostream : public std::basic_ostream<CharT, Traits>
instead of:
template < typename CharT, typename Traits = std::char_traits<CharT> >
class basic_tostream : std::basic_ostream<CharT, Traits>
Key difference being public
. That's what the 'std::basic_ostream' is an inaccessible base of 'basic_tostream'
error message is about.
Licensed under: CC-BY-SA with attribution
Not affiliated with StackOverflow