customize cout

Question

How can I derive a class from cout so that, for example, writing to it

new_cout << \"message\";

would be equivalent to

Answer 1

class Log
{
public:
    Log(const std::string &funcName)
    {
        std::cout << funcName << ": ";
    }

    template 
    Log &operator<<(const T &v)
    {
        std::cout << v;
        return *this;
    }

    ~Log()
    {
        std::cout << " [end of message]" << std::endl;
    }
};

#define MAGIC_LOG Log(__FUNCTION__)

Hence:

MAGIC_LOG << "here's a message";
MAGIC_LOG << "here's one with a number: " << 5;