ostream_withassign( streambuf* psb );
ostream_withassign();
psb
A pointer to an existing object of a streambuf-derived class.
The first constructor makes a ready-to-use object of type ostream_withassign, complete with an attached streambuf object.
The second constructor makes an object but does not initialize it. You must subsequently use the streambuf assignment operator to attach the streambuf object, or you must use the ostream assignment operator to initialize this object to match the specified object.
ostream_withassign::operator =