C++ stream as a parameter when overloading operator<<
- by TheOm3ga
I'm trying to write my own logging class and use it as a stream:
logger L;
L << "whatever" << std::endl;
This is the code I started with:
#include <iostream>
using namespace std;
class logger{
public:
template <typename T>
friend logger& operator <<(logger& log, const T& value);
};
template <typename T>
logger& operator <<(logger& log, T const & value) {
// Here I'd output the values to a file and stdout, etc.
cout << value;
return log;
}
int main(int argc, char *argv[])
{
logger L;
L << "hello" << '\n' ; // This works
L << "bye" << "alo" << endl; // This doesn't work
return 0;
}
But I was getting an error when trying to compile, saying that there was no definition for operator<<:
pruebaLog.cpp:31: error: no match for ‘operator<<’ in ‘operator<< [with T = char [4]](((logger&)((logger*)operator<< [with T = char [4]](((logger&)(& L)), ((const char (&)[4])"bye")))), ((const char (&)[4])"alo")) << std::endl’
So, I've been trying to overload operator<< to accept this kind of streams, but it's driving me mad. I don't know how to do it. I've been loking at, for instance, the definition of std::endl at the ostream header file and written a function with this header:
logger& operator <<(logger& log, const basic_ostream<char,char_traits<char> >& (*s)(basic_ostream<char,char_traits<char> >&))
But no luck. I've tried the same using templates instead of directly using char, and also tried simply using "const ostream& os", and nothing.
Another thing that bugs me is that, in the error output, the first argument for operator<< changes, sometimes it's a reference to a pointer, sometimes looks like a double reference...
