這裏是從C一些代碼++的書,我一直在閱讀展示瞭如何創建自己的智能指針:自定義智能指針代碼issue- couldnt智能指針最終在堆上?
template <typename T>
class SuperSmartPointer
{
public:
explicit SuperSmartPointer(T* inPtr);
virtual ~SuperSmartPointer();
SuperSmartPointer(const SuperSmartPointer<T>& src);
SuperSmartPointer<T>& operator=(const SuperSmartPointer<T>& rhs);
const T& operator*() const;
const T* operator->() const;
T& operator*();
T* operator->();
operator void*() const { return mPtr; }
protected:
T* mPtr;
static std::map<T*, int> sRefCountMap;
void finalizePointer();
void initPointer(T* inPtr);
};
template <typename T>
std::map<T*, int> SuperSmartPointer<T>::sRefCountMap;
template <typename T>
SuperSmartPointer<T>::SuperSmartPointer(T* inPtr)
{
initPointer(inPtr);
}
template <typename T> SuperSmartPointer<T>::SuperSmartPointer(const SuperSmartPointer<T>& src)
{
initPointer(src.mPtr);
}
template <typename T>
SuperSmartPointer<T>& SuperSmartPointer<T>::operator=(const SuperSmartPointer<T>& rhs)
{
if (this == &rhs) {
return *this;
}
finalizePointer();
initPointer(rhs.mPtr);
return *this;
}
template <typename T>
SuperSmartPointer<T>::~SuperSmartPointer()
{
finalizePointer();
}
template<typename T>
void SuperSmartPointer<T>::initPointer(T* inPtr)
{
mPtr = inPtr;
if (sRefCountMap.find(mPtr) == sRefCountMap.end()) {
sRefCountMap[mPtr] = 1;
} else {
sRefCountMap[mPtr]++;
}
}
template<typename T>
void SuperSmartPointer<T>::finalizePointer()
{
if (sRefCountMap.find(mPtr) == sRefCountMap.end()) {
throw std::runtime_error(「ERROR: Missing entry in map!」);
}
sRefCountMap[mPtr]--;
if (sRefCountMap[mPtr] == 0) {
// No more references to this object--delete it and remove from map
sRefCountMap.erase(mPtr);
delete mPtr;
mPtr = nullptr;
}
}
template <typename T>
const T* SuperSmartPointer<T>::operator->() const
{
return mPtr;
}
template <typename T>
const T& SuperSmartPointer<T>::operator*() const
{
return *mPtr;
}
template <typename T>
T* SuperSmartPointer<T>::operator->()
{
return mPtr;
}
template <typename T>
T& SuperSmartPointer<T>::operator*()
{
return *mPtr;
}
我這段代碼的問題/我的問題是,肯定有人可以實例化這個智能指針的對象類使用new()
運算符,在堆上有智能指針,因此會管理共享指針的內存?如果new()
運算符被過載/阻止,要使其成爲正確的共享指針?
編輯:不應該動態內存分配的自定義智能指針本身被阻止?
好的 - 我明白了你的觀點。謝謝 – user997112