nullstream.adoc
1.53 KB
Null Streams, <boost/io/nullstream.hpp>
Description
The header <boost/io/nullstream.hpp> provides the class template
boost::io::basic_nullbuf which is a null stream buffer and class template
boost::io::basic_onullstream which is a null stream.
Example
The following program passes a null stream to a function.
#include <boost/io/ostream_joiner.hpp>
#include <fstream>
void setup(std::ostream& log);
int main(int argc, char* argv[])
{
if (argc == 2) {
std::ofstream file(argv[1]);
setup(file);
} else {
boost::io::onullstream none;
setup(none);
}
}Reference
Header Synopsis
namespace boost {
namespace io {
template<class CharT, class Traits = std::char_traits<Char> >
class basic_nullbuf
: public std::basic_streambuf<CharT, Traits> {
protected:
typename Traits::int_type overflow(typename Traits::int_type c) override;
std::streamsize xsputn(const CharT*, std::streamsize n) override;
};
template<class CharT, class Traits = std::char_traits<CharT> >
class basic_onullstream
: public std::basic_ostream<CharT, Traits> {
public:
basic_onullstream();
};
typedef basic_onullstream<char> onullstream;
typedef basic_onullstream<wchar_t> wonullstream;
} // io
} // boostAcknowledgments
Glen Fernandes implemented basic_nullbuf and basic_onullstream.