Problem with template

I want to write an auto_ptr implementation for Core Foundation objects, but I'm having a little problem with making a converting constructor.

Code:

---

template <typename T>
class CF_auto_ptr
{
        public:
                CF_auto_ptr(T p = 0);
                ~CF_auto_ptr();
                CF_auto_ptr<T>(CF_auto_ptr<T>& rhs);
                CF_auto_ptr<T>& operator=(CF_auto_ptr<T> rhs);
               
                T get() const;
                void release();
                void reset(T p);
        private:
                T p;
};

template <typename T>
CF_auto_ptr<T>::CF_auto_ptr(T p)
        : p(p)
{}

template <typename T>
CF_auto_ptr<T>::~CF_auto_ptr()
{
        if (p)
        {
                CFRelease(p);
        }
}

template <typename T>
CF_auto_ptr<T>::CF_auto_ptr(CF_auto_ptr<T>& rhs)
{
        p = rhs.get();
        rhs.release();
}

template <typename T>
CF_auto_ptr<T>& CF_auto_ptr<T>::operator=(CF_auto_ptr<T> rhs)
{
        p = rhs.get();
        rhs.release();
        return *this;
}

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I thought this would do it, but I get errors when I use it like this:

Code:

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CF_auto_ptr<CFBundleRef> main_bundle = CFBundleGetMainBundle();

---

Code:

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error: no matching function for call to 'CF_auto_ptr<__CFBundle*>::CF_auto_ptr(CF_auto_ptr<__CFBundle*>)'

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Code:

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candidates are: CF_auto_ptr<T>::CF_auto_ptr(CF_auto_ptr<T>&) [with T = __CFBundle*]

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The problem is that if you accept an argument by non-const reference, you can't pass a temporary to it.

I guess, here you could call your other constructor:

Code:

---

CF_auto_ptr<CFBundleRef> main_bundle(CFBundleGetMainBundle());

---

In any case, mimicking the semantics of std::auto_ptr (ownership transfer) might not be worth it (it is practically a deprecated class).

Instead, if you want, you should be easily able to share resources with boost::shared_ptr (or std::tr1::shared_ptr), which allow to use a custom deleter. Or you might just make you auto_ptr non-copyable (like std::tr1::unique_ptr or boost::scoped_ptr).