ostringstream overloading const char * with the void *

Question

im having an issue with the ostream, I have written a very basic macro that should print out its parameters.

Please see example code below:

#define LOG Message(__FILE__, __LINE__,__func__)

class Message : public std::ostringstream 
{
    public:
        Message(const char *param1, int param2, const char *param3)
        {
            *this<<param3<<"("<<param1<<":"<<param2<<")";
        }
        ~Message()
        {
            *this<<endl;
            cout<< rdbuf()->str();
        }
};


int main()
{
    int integer = 1;
    string str = "XYZ";

    LOG<<integer<<"DEBUGLOG1: "<<str<<" "<<integer;
    return 0;
}

The problem is if I use:

LOG << "LOG1: " << str << " " << integer;

The output prints the Address* of the const char* "LOG1: " rather than the value.

But, If I use:

LOG << integer << "DEBUGLOG1: " << str << " " << integer;

The output works perfect, printing the integer value and the char value.

it looks like instead of using ostream& operator<< (ostream& out, const char* s );

it is using ostream& operator<< (const void* val); ?

Can anyone shed any light on what can be done to overcome this overloading please?

Thanks in advance

Answer 1

The problem is that Message(...) is a temporary. The temporary cannot bind to a non-const reference parameter for operator<<.

It can only be used with member functions and operators, like ostream::operator<<(int).

The odd thing is that the member operator returns a reference which can, in turn, be used with the non-member operators.