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

As Luc Hermitte noted, there is "Logging In C++" article which describes very neat approach to solve this problem. In a nutshell, given you have a function like the following:

void LogFunction(const std::string& str) {
    // write to socket, file, console, e.t.c
    std::cout << str << std::endl;
}

it is possible to write a wrapper to use it in std::cout like way:

#include 
#include 

#define LOG(loggingFuntion) \
    Log(loggingFuntion).GetStream()

class Log {
    using LogFunctionType = std::function;

public:
    explicit Log(LogFunctionType logFunction) : m_logFunction(std::move(logFunction)) { }
    std::ostringstream& GetStream() { return m_stringStream; }
    ~Log() { m_logFunction(m_stringStream.str()); }

private:
    std::ostringstream m_stringStream;
    LogFunctionType m_logFunction;
};

int main() {
    LOG(LogFunction) << "some string " << 5 << " smth";
}

(online demo)

Also, there is very nice solution provided by Stewart.