[lug] simple iostream bug?

Thu Mar 14 17:28:51 MST 2002

>>>>> "DS" == D Stimits <stimits at idcomm.com> writes:

DS> Basically it is just a function to take a reference to an ostream,
DS> insert some text, and return it by reference. In this case it is
DS> cout.

a more c++ish idiom (at least to my eyes) would be to create an
object, and then print the object (using "<<") onto the output stream.

there's a nice idiom for making "<<" behave polymorphically, as well:

| #include <iostream>
| using std::cout;
| 
| #include <iomanip>
| using std::endl;
| 
| #include <string>
| using std::string;
| 
| class HTTPHeader {
| private:
|     int    status_code_;
|     string content_type_;
| public:
|     HTTPHeader(int status_code,
|                const string & content_type)
|       : status_code_(status_code), 
|         content_type_(content_type)
|     {}
| 
|     virtual ostream & print_to_ostream(ostream & os) const;
|     static string status_text(int status_code);
| };
| 
| ostream & 
| HTTPHeader::print_to_ostream(ostream & os) const
| {
|     return os << status_code_ << " " << status_text(status_code_) << endl
|               << "Content-type: " << content_type_ << endl;
| }
| 
| string
| HTTPHeader::status_text(int status_code)
| {
|     switch (status_code)
|     {
|     case 200: return "Ok";
|     default:  return "Unknown Status";
|     }
| }
| 
| ostream &
| operator << (ostream & os, const HTTPHeader & h)
| {
|     return h.print_to_ostream(os);
| }
| 
| int main(int argc, char * argv [])
| {
|     HTTPHeader header(200, "text/html");
| 
|     cout << header << endl
|          << "<html>" << endl
|          << "  <head><title>test</title</head>" << endl
|          << "  <body><p>foo</p</body>" << endl
|          << "</html>" << endl;
| 
|     return 0;
| }