/g/ - >mfw trying to learn RAII #include template cla - Technology

Anonymous

07/25/24(Thu)04:32:00 No.101563599

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Anonymous 07/25/24(Thu)04:32:00 No.101563599 Archived

>mfw trying to learn RAII

#include <iostream>

template<typename T>
class Auto_ptr5
{
    T* m_ptr {};
public:
    Auto_ptr5(T* ptr = nullptr)
        : m_ptr { ptr }
    {
    }

    ~Auto_ptr5()
    {
        delete m_ptr;
    }

    // Copy constructor -- no copying allowed!
    Auto_ptr5(const Auto_ptr5& a) = delete;

    // Move constructor
    // Transfer ownership of a.m_ptr to m_ptr
    Auto_ptr5(Auto_ptr5&& a) noexcept
        : m_ptr(a.m_ptr)
    {
        a.m_ptr = nullptr;
    }

    // Copy assignment -- no copying allowed!
    Auto_ptr5& operator=(const Auto_ptr5& a) = delete;

    // Transfer ownership of a.m_ptr to m_ptr
    Auto_ptr5& operator=(Auto_ptr5&& a) noexcept
    {
        // Self-assignment detection
        if (&a == this)
            return *this;

        // Release any resource we're holding
        delete m_ptr;

        // Transfer ownership of a.m_ptr to m_ptr
        m_ptr = a.m_ptr;
        a.m_ptr = nullptr;

        return *this;
    }

    T& operator*() const { return *m_ptr; }
    T* operator->() const { return m_ptr; }
    bool isNull() const { return m_ptr == nullptr; }
};

Anonymous
07/25/24(Thu)04:35:42 No.101563624

Anonymous 07/25/24(Thu)04:35:42 No.101563624

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>m_ptr
>Auto_ptr5

Anonymous
07/25/24(Thu)04:58:40 No.101563753

Anonymous 07/25/24(Thu)04:58:40 No.101563753

>>101563599
It seems you are trying to implement unique_ptr, i'll give you some tips:
Always theck if this->m_ptr is not null before calling delete
For your assignment operators, you can use friend to explicitly qualify what kind of operations are allowed i.e
// Moves self into other
friend Auto_ptr5& operator=(Auto_ptr5& self, Auto_ptr5&& other)
{
    if (self.m_ptr) delete self.m_ptr;
    
    self.m_ptr = other.m_ptr;
    other.m_ptr = nullptr

    return self;
}
You can also use the deducing this feature, but I don't think it's very stable right now

Also you should provide a way to automatically create your auto_ptr i.e
template <class U, class... Ts>
decltype(auto) make_autoptr5(Ts&&... ts)
{
    return Auto_ptr5(new U(std::forward<Ts>(ts)...));
}
If i were you, i'd disable the possibility to create an Auto_ptr from a raw pointer or throw an exception if it is null because your dereference method might crash your program when least expect it