handle.h

来自「包括ARM开发环境的使用和一些调试用的源程序」· C头文件 代码 · 共 52 行

#ifndef GUARD_Handle_h
#define GUARD_Handle_h

template <class T> class Handle {
public:
	Handle(): p(0) { }
	Handle(const Handle& s): p(0) { if (s.p) p = s.p->clone(); }
	Handle& operator=(const Handle&);
	~Handle() { delete p; }

	Handle(T* t): p(t) { }

	operator bool() const { return p; }
	T& operator*() const;
	T* operator->() const;

private:
	T* p;
};

#include <stdexcept>

using std::runtime_error;

template <class T>
Handle<T>& Handle<T>::operator=(const Handle& rhs)
{
	if (&rhs != this) {
		delete p;
		p = rhs.p ? rhs.p->clone() : 0;
	}
	return *this;
}

template <class T>
T& Handle<T>::operator*() const
{
	if (p) 	
		return *p;
	throw runtime_error("unbound Handle");
}

template <class T>
T* Handle<T>::operator->() const
{
	if (p)
		return p;
	throw runtime_error("unbound Handle");
}

#endif