boost::openmethod::virtual_ptr<SmartPtr, Registry>::virtual_ptr

Construct‐move from a virtual pointer to a derived class

Synopsis

Declared in <boost/openmethod/core.hpp>

template<class Other>
requires SameSmartPtr<SmartPtr, Other, Registry> &&
            std::is_constructible_v<SmartPtr, Other&&>
virtual_ptr(virtual_ptr<Other, Registry>&& other);

Description

Move the object pointer from other to this. Copy the v‐table pointer from other.

Other is not required to be a pointer to a polymorphic class.

Examples

Move‐constructing from a shared virtual_ptr:

// classes not required to be polymorphic
struct Animal {};
struct Cat : Animal {};
struct Dog : Animal {};

BOOST_OPENMETHOD_CLASSES(Animal, Cat, Dog);

virtual_ptr<std::shared_ptr<Dog>> snoopy = make_shared_virtual<Dog>();
Dog* dog = snoopy.get();

virtual_ptr<std::shared_ptr<Animal>> p = std::move(snoopy);

BOOST_TEST(p.get() == dog);
BOOST_TEST(p.vptr() == default_registry::static_vptr<Dog>);
BOOST_TEST(snoopy.get() == nullptr);

Move‐constructing from a unique virtual_ptr:

unique_virtual_ptr<Dog> snoopy = make_unique_virtual<Dog>();
Dog* moving = snoopy.get();

unique_virtual_ptr<Animal> p = std::move(snoopy);

BOOST_TEST(p.get() == moving);
BOOST_TEST(p.vptr() == default_registry::static_vptr<Dog>);
BOOST_TEST(snoopy.get() == nullptr);

Requirements

  • SmartPtr and Other must be instantiated from the same template ‐ e.g. both std::shared_ptr or both std::unique_ptr.

  • Other must be a smart pointer to a class derived from element_type.

  • SmartPtr must be constructible from Other&&.

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