From http://www.dbj.org/2006/05/11/wtl-initialization-com-and-namespaces-synergy/

WTL INIT 2006.h

#pragma once
/*
Copyright 2006 - 2018 [email protected]

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

http ://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

/* set to 1 if using com */
#define DBJCOM 0

#define WIN32_LEAN_AND_MEAN
#define VC_EXTRALEAN
#include <Windows.h>
#include <combaseapi.h>

namespace dbj {

namespace win {
#if DBJCOM		
namespace com {
namespace {
/*
In anonymous namespace we hide the auto-initializer
This ensures that COM is initialized “as soon as possible”
This mechanism really works. Convince yourself once through the
debugger, and then just forget about COM init/uninit.
*/
struct __declspec(novtable)
	COMAUTOINIT
	{
	unsigned int & counter()
	{
	static unsigned int counter_ = 0;
	return counter_;
	}
/*
If you call ::CoInitialize(NULL), after this method is used
most likely the HRESULT will be :
hRes = 0×80010106 — Cannot change thread mode after it is set.
*/
	COMAUTOINIT()
	{
	const UINT & ctr = (counter())++;
	if (0 == ctr)
#if ( defined(_WIN32_DCOM)  || defined(_ATL_FREE_THREADED))
	HRESULT result = ::CoInitializeEx(NULL, COINIT_MULTITHREADED);
#else
	HRESULT result = ::CoInitialize(NULL);
#endif
	/*TODO: log the result here*/
	}

	~COMAUTOINIT()
	{
	const UINT ctr = --(counter());
	if (ctr < 1)
	::CoUninitialize();
	}

	};
	static const COMAUTOINIT wtlcomautoinit__{};
} // anonspace
} // com
} // win
} // dbj
#endif // DBJCOM
/*
If problems with them, one can undef the macros defined in here

#undef DBJINL // static __forceinline 
#undef WIN32_LEAN_AND_MEAN
#undef VC_EXTRALEAN
*/

2017 Mar. Update