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 << someInt << someString;   debugLogger.log(ss.str()); 

instead, it would be much more convenient to use it like a stream as in:

debugLogger << someInt << someString; 

Is there a better way than forwarding everything to an internal stringstream instance? If’d do this, when would i need to flush?

Answer 1

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

template <typename T> 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.