How to use my logging class like a std C++ stream?

Question

I\'ve a working logger class, which outputs some text into a richtextbox (Win32, C++). Problem is, i always end up using it like this:

stringstream ss;  
ss          


        

Answer 1

You need to implement operator << appropriately for your class. The general pattern looks like this:

template 
logger& operator <<(logger& log, T const& value) {
    log.your_stringstream << value;
    return log;
}

Notice that this deals with (non-const) references since the operation modifies your logger. Also notice that you need to return the log parameter in order for chaining to work:

log << 1 << 2 << endl;
// is the same as:
((log << 1) << 2) << endl;

If the innermost operation didn't return the current log instance, all other operations would either fail at compile-time (wrong method signature) or would be swallowed at run-time.