C++ concepts: UnformattedOutputFunction

Requirements

A UnformattedOutputFunction is a stream output function that performs the following:

• Constructs an object of type basic_ostream::sentry with automatic storage duration, which performs the following

• if eofbit or badbit are set on the output stream, sets the failbit as well, and if exceptions on failbit are enabled in this output stream's exception mask, throws ios_base::failure.
• flushes the tie()'d output stream, if applicable.

• Checks the status of the sentry by calling sentry::operator bool(), which is equivalent to basic_ios::good.
• If the sentry returned false or sentry's constructor threw an exception, no output takes place
• If the sentry returned true, attempts to perform the desired output by inserting the characters into the output stream as if by calling rdbuf()->sputc() or rdbuf()->xsputn(). Additionally, rdbuf()->overflow() and rdbuf()->sync() may be called, but no other virtual member function of std::basic_streambuf.

• if an exception is thrown during output, sets badbit in the output stream. If exceptions on badbit are enabled in this stream's exception mask, the exception is also rethrown.
• If no exception was thrown, returns the value specified by the function.

• In any event, whether terminating by exception or returning, the sentry's destructor is called before leaving this function.

Standard library

The following standard library functions are UnformattedOutputFunctions.

• basic_ostream::operator<<(basic_streambuf*)
• basic_ostream::put
• basic_ostream::write
• basic_ostream::flush