ATLCOM.h里面模版定义两次，这两个有什么联系，为什么要定义两次？
template <class ThreadModel>
class CComObjectRootEx : public CComObjectRootBase
{
public:
typedef ThreadModel _ThreadModel;
typedef _ThreadModel::AutoCriticalSection _CritSec;
typedef CComObjectLockT<_ThreadModel> ObjectLock;
ULONG InternalAddRef()
{
ATLASSERT(m_dwRef != -1L);
return _ThreadModel::Increment(&m_dwRef);
}
ULONG InternalRelease()
{
ATLASSERT(m_dwRef > 0);
return _ThreadModel::Decrement(&m_dwRef);
}
void Lock() {m_critsec.Lock();}
void Unlock() {m_critsec.Unlock();}
private:
_CritSec m_critsec;
};
template <>
class CComObjectRootEx<CComSingleThreadModel> : public CComObjectRootBase
{
public:
typedef CComSingleThreadModel _ThreadModel;
typedef _ThreadModel::AutoCriticalSection _CritSec;
typedef CComObjectLockT<_ThreadModel> ObjectLock;
ULONG InternalAddRef()
{
ATLASSERT(m_dwRef != -1L);
return _ThreadModel::Increment(&m_dwRef);
}
ULONG InternalRelease()
{
return _ThreadModel::Decrement(&m_dwRef);
}
void Lock() {}
void Unlock() {}
};
