C++ Logging using ATL (subset of MFC)

Logging.h

/*
Copyright (c) 2011 Christoph Stoepel

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*/

#ifndef __LOGGING_H__
#define __LOGGING_H__

#pragma once

#include <atlsimpcoll.h>

namespace Logging
{
	enum LOG_LEVEL
	{
		LOG_LEVEL_NONE = 0,
		LOG_LEVEL_DEBUG = 1,
		LOG_LEVEL_INFO = 2,
		LOG_LEVEL_WARN = 3,
		LOG_LEVEL_ERROR = 4,
		LOG_LEVEL_FATAL = 5
	};

	class CLogMessage
	{
	public:
		CString m_szMessage;

	public:
		CLogMessage(LPCTSTR szMsg) : m_szMessage(szMsg) { }
		CLogMessage(const CLogMessage& msg) : m_szMessage(msg.m_szMessage) { }
		CLogMessage(LPCTSTR szFormat, ...) 
		{
			va_list args;
			va_start(args, szFormat);
			m_szMessage.FormatV(szFormat, args);
			va_end(args);
		}

		operator LPCTSTR() const { return (LPCTSTR)m_szMessage; }
		CLogMessage& operator=(const CLogMessage& msg) { m_szMessage = msg.m_szMessage; return *this; }
		bool operator==(const CLogMessage& msg) const { return m_szMessage.Compare(msg.m_szMessage) == 0; }
	};

	class ILogTarget
	{
	public:
		virtual ~ILogTarget() { }
		virtual bool IsEnabled(LOG_LEVEL lvl) = 0;
		virtual void Append(LPCTSTR szMsg) = 0;
	};

	class CLogTargetBase : public ILogTarget
	{
	protected:
		LOG_LEVEL m_nLevel;

	public:
		CLogTargetBase(LOG_LEVEL lvl) : m_nLevel(lvl) { }
		virtual ~CLogTargetBase() {}
		virtual bool IsEnabled(LOG_LEVEL lvl) { return m_nLevel <= lvl; }
	};

	class CLogTargetDebugger : public CLogTargetBase
	{
	public:
		CLogTargetDebugger(LOG_LEVEL lvl) : CLogTargetBase(lvl) { }
		virtual ~CLogTargetDebugger() { }
		virtual void Append(LPCTSTR szMsg) { ::OutputDebugString(szMsg); }
	};

	class CLogTargetMessageBox : public CLogTargetBase
	{
	public:
		CLogTargetMessageBox(LOG_LEVEL lvl) : CLogTargetBase(lvl) { }
		virtual ~CLogTargetMessageBox() { }
		virtual void Append(LPCTSTR szMsg) { ::AtlMessageBox(NULL, szMsg); }
	};

	class CLogger
	{
	private:
		DWORD m_dwLogStart;
		CSimpleArray <ILogTarget*> m_pTargets;

	public:
		CLogger();
		~CLogger();
		
		void AddTarget(ILogTarget* pTarget);
		void Log(LOG_LEVEL lvl, LPCTSTR szMsg, LPCTSTR szFile, LPCTSTR szFunction, int nLine);
	};

	class CLoggerFactory
	{
	private:
		static CLogger m_SingletonInstance;	// TODO: write a real singleton/ factory pattern implementation

	public:
		static CLogger* getDefaultInstance() { return &m_SingletonInstance; }
	};
}

#define WIDEN2(x) L##x
#define WIDEN(x) WIDEN2(x)

#define __LOGMSG(lvl, msg, file, func, line) Logging::CLoggerFactory::getDefaultInstance()->Log(lvl, msg, file, func, line)

#ifdef UNICODE
	#define LOGMSG(lvl, msg)  __LOGMSG(lvl, msg, WIDEN(__FILE__), WIDEN(__FUNCSIG__), __LINE__)
	#define LOGMSG_DEBUG(msg) __LOGMSG(Logging::LOG_LEVEL_DEBUG, msg, WIDEN(__FILE__), WIDEN(__FUNCTION__), __LINE__)
	#define LOGMSG_INFO(msg)  __LOGMSG(Logging::LOG_LEVEL_INFO, msg, WIDEN(__FILE__), WIDEN(__FUNCTION__), __LINE__)
	#define LOGMSG_WARN(msg)  __LOGMSG(Logging::LOG_LEVEL_WARN, msg, WIDEN(__FILE__), WIDEN(__FUNCTION__), __LINE__)
	#define LOGMSG_ERROR(msg) __LOGMSG(Logging::LOG_LEVEL_ERROR, msg, WIDEN(__FILE__), WIDEN(__FUNCTION__), __LINE__)
	#define LOGMSG_FATAL(msg) __LOGMSG(Logging::LOG_LEVEL_FATAL, msg, WIDEN(__FILE__), WIDEN(__FUNCTION__), __LINE__)
#else
	#define LOGMSG(lvl, msg)  __LOGMSG(lvl, msg, __FILE__, __FUNCSIG__, __LINE__)
	#define LOGMSG_DEBUG(msg) __LOGMSG(Logging::LOG_LEVEL_DEBUG, msg, __FILE__, __FUNCTION__, __LINE__)
	#define LOGMSG_INFO(msg)  __LOGMSG(Logging::LOG_LEVEL_INFO, msg, __FILE__, __FUNCTION__, __LINE__)
	#define LOGMSG_WARN(msg)  __LOGMSG(Logging::LOG_LEVEL_WARN, msg, __FILE__, __FUNCTION__, __LINE__)
	#define LOGMSG_ERROR(msg) __LOGMSG(Logging::LOG_LEVEL_ERROR, msg, __FILE__, __FUNCTION__, __LINE__)
	#define LOGMSG_FATAL(msg) __LOGMSG(Logging::LOG_LEVEL_FATAL, msg, __FILE__, __FUNCTION__, __LINE__)
#endif // UNICODE

#endif // __LOGGING_H__

Just stumbled upon this. Very nice. The only thing I'm missing is formatting.
A couple of questions:

• Is this the latest version?
• Is there a repository for these files?
• What did you mean by "write a real singleton/ factory pattern implementation"?

P.S. sorry for being a necrophile, I know the files are from 2011.

Implementation of CLogger??

Implementation In https://gist.github.com/Chrisso/1348011