template class Poco::SharedPtr

Overview

SharedPtr is a “smart” pointer for classes implementing reference counting based garbage collection. More…

#include <SharedPtr.h>

template <
    class C,
    class RC = ReferenceCounter,
    class RP = ReleasePolicy<C>
    >
class SharedPtr
{
public:
    // construction

    SharedPtr();
    SharedPtr(C* ptr);

    template <
        class Other,
        class OtherRP
        >
    SharedPtr(const SharedPtr<Other, RC, OtherRP>& ptr);

    SharedPtr(const SharedPtr& ptr);

    // methods

    SharedPtr&
    assign(C* ptr);

    SharedPtr&
    assign(const SharedPtr& ptr);

    template <
        class Other,
        class OtherRP
        >
    SharedPtr&
    assign(const SharedPtr<Other, RC, OtherRP>& ptr);

    SharedPtr&
    operator=(C* ptr);

    SharedPtr&
    operator=(const SharedPtr& ptr);

    template <
        class Other,
        class OtherRP
        >
    SharedPtr&
    operator=(const SharedPtr<Other, RC, OtherRP>& ptr);

    void
    swap(SharedPtr& ptr);

    template <class Other>
    SharedPtr<Other, RC, RP>
    cast() const;

    template <class Other>
    SharedPtr<Other, RC, RP>
    unsafeCast() const;

    C*
    operator->();

    const C*
    operator->() const;

    C&
    operator*();

    const C&
    operator*() const;

    C*
    get();

    const C*
    get() const;

    operator C*();
    operator const C *() const;

    bool
    operator!() const;

    bool
    isNull() const;

    bool
    operator==(const SharedPtr& ptr) const;

    bool
    operator==(const C* ptr) const;

    bool
    operator==(C* ptr) const;

    bool
    operator!=(const SharedPtr& ptr) const;

    bool
    operator!=(const C* ptr) const;

    bool
    operator!=(C* ptr) const;

    bool
    operator<(const SharedPtr& ptr) const;

    bool
    operator<(const C* ptr) const;

    bool
    operator<(C* ptr) const;

    bool
    operator<=(const SharedPtr& ptr) const;

    bool
    operator<=(const C* ptr) const;

    bool
    operator<=(C* ptr) const;

    bool
    operator>(const SharedPtr& ptr) const;

    bool
    operator>(const C* ptr) const;

    bool
    operator>(C* ptr) const;

    bool
    operator>=(const SharedPtr& ptr) const;

    bool
    operator>=(const C* ptr) const;

    bool
    operator>=(C* ptr) const;

    int
    referenceCount() const;
};

Detailed Documentation

SharedPtr is a “smart” pointer for classes implementing reference counting based garbage collection.

SharedPtr is thus similar to AutoPtr. Unlike the AutoPtr template, which can only be used with classes that support reference counting, SharedPtr can be used with any class. For this to work, a SharedPtr manages a reference count for the object it manages.

SharedPtr works in the following way: If an SharedPtr is assigned an ordinary pointer to an object (via the constructor or the assignment operator), it takes ownership of the object and the object’s reference count is initialized to one. If the SharedPtr is assigned another SharedPtr, the object’s reference count is incremented by one. The destructor of SharedPtr decrements the object’s reference count by one and deletes the object if the reference count reaches zero. SharedPtr supports dereferencing with both the -> and the * operator. An attempt to dereference a null SharedPtr results in a NullPointerException being thrown. SharedPtr also implements all relational operators and a cast operator in case dynamic casting of the encapsulated data types is required.

Methods

template <class Other>
SharedPtr<Other, RC, RP>
cast() const

Casts the SharedPtr via a dynamic cast to the given type.

Returns an SharedPtr containing NULL if the cast fails. Example: (assume class Sub: public Super)

SharedPtr<Super> super(new Sub());
SharedPtr<Sub> sub = super.cast<Sub>();
poco_assert (sub.get());

template <class Other>
SharedPtr<Other, RC, RP>
unsafeCast() const

Casts the SharedPtr via a static cast to the given type.

Example: (assume class Sub: public Super)

SharedPtr<Super> super(new Sub());
SharedPtr<Sub> sub = super.unsafeCast<Sub>();
poco_assert (sub.get());