simple C++ iostream log

iolog.h

#pragma once

#include <ostream>
#include <fstream>

using namespace std;

class Log
{
typedef std::ostream& (*ostream_manipulator)(std::ostream&);

public:
	enum eLevel { Debug, Error, Info };

	Log(ostream& m_stream) : stream(m_stream), level(Info) { }

	template<typename T> void log(const T& v)
	{
		switch(level)
		{
		case Debug:
			#ifdef DEBUG
			stream << "DEBUG: " << v;
			#endif
			break;
		case Error:
			stream << "ERROR: " << v;
			break;
		case Info:
			stream << v;
			break;
		}
	}

	template<typename T> Log& operator<<(const T& v)
	{
		log(v);
		return *this;
	}

	// allow manipulators for the stream (endl, ...)
	Log& operator<<(ostream_manipulator pf)
	{
	   stream << pf;
	   return *this;
	}

	Log& operator<<(eLevel l) { level = l; }

protected:
	ostream& stream;
	eLevel level;
};

class FileLog : Log
{
public:
	FileLog(const string& filename) : file(filename.c_str(), ios::out | ios::ate), Log(file) { }

private:
	ofstream file;
};