C++ RAII mutex locking, bound to userdata

ptrlock_macro.cpp

// Auto-unlock wrapper for larger operations
/*
Exmaple usage:

struct MyStruct {
	PtrLock<decltype(m_value)> getValues()
	{
		return PtrLock<decltype(m_value)>(m_lock, &m_value);
	}

private:
	std::mutex m_lock;
	std::vector<int> m_value;
};

static void mycaller()
{
	MyStruct s;
	auto values = s.getValues();
	values->push_back(42);
}
*/


template<typename T>
class PtrLock {
public:
	PtrLock(std::mutex &m, T *ptr) :
		m_mutex(m), m_ptr(ptr)
	{
		if (ptr)
			m.lock();
	}

	~PtrLock()
	{
		if (m_ptr)
			m_mutex.unlock();
	}

	DISABLE_COPY(PtrLock)

	void release()
	{
		if (m_ptr)
			m_mutex.unlock();
		m_ptr = nullptr;
	}

	inline T *ptr() const { return m_ptr; }
	// Synthetic sugar
	inline T *operator->() const { return m_ptr; }
	// Validation check
	inline bool operator!() const { return !m_ptr; }

private:
	std::mutex &m_mutex;
	T *m_ptr;
};