Basic eventually

template<returnable T, bool Exception>
class basic_eventually : private lf::impl::immovable<basic_eventually<T, Exception>>

A wrapper to delay construction of an object.

An eventually is either empty, contains an object of type T or, (if Exception is true) contains an exception. Assignment to an empty eventually will construct an object of type T inside the eventually.

Public Types

using value_type = T

The type of the object stored in the eventually.

Public Functions

inline basic_eventually() noexcept

Construct an empty eventually.

inline basic_eventually() noexcept

Construct an empty eventually.

inline basic_eventually() noexcept

Construct an empty eventually.

inline ~basic_eventually() noexcept

Destroy the eventually object and the contained object.

inline auto empty() const noexcept -> bool

Check if the eventually is empty.

inline auto exception() && noexcept -> std::exception_ptr&&

Access the stored exception, has_exception() must be true.

inline auto exception() & noexcept -> std::exception_ptr&

Access the stored exception, has_exception() must be true.

inline auto exception() const && noexcept -> std::exception_ptr const&&

Access the stored exception, has_exception() must be true.

inline auto exception() const & noexcept -> std::exception_ptr const&

Access the stored exception, has_exception() must be true.

inline auto has_exception() const noexcept -> bool

Test is there is an exception stored in the eventually.

inline auto has_value() const noexcept -> bool

Check if there is a value stored in the eventually.

inline auto operator*() && noexcept -> std::add_rvalue_reference_t<T>

Access the stored value, has_value() must be true.

inline auto operator*() & noexcept -> std::add_lvalue_reference_t<T>

Access the stored value, has_value() must be true.

inline auto operator*() const && noexcept -> std::add_rvalue_reference_t<T const>

Access the stored value, has_value() must be true.

inline auto operator*() const && noexcept -> T

Access the stored value, has_value() must be true.

This will not decay T&& to T&, nor will it promote T& to T&&.

inline auto operator*() const & noexcept -> std::add_lvalue_reference_t<std::remove_reference_t<T>>

Access the stored value, has_value() must be true.

This will decay T&& to T& just like using a T && reference would.

inline auto operator*() const & noexcept -> std::add_lvalue_reference_t<T const>

Access the stored value, has_value() must be true.

inline auto operator->() const noexcept -> std::add_pointer_t<T>

Access the stored value, has_value() must be true.

inline auto operator->() const noexcept -> std::add_pointer_t<T const>

Access the stored value, has_value() must be true.

inline auto operator->() noexcept -> std::add_pointer_t<T>

Access the stored value, has_value() must be true.

template<impl::safe_ref_bind_to<T> U>
inline auto operator=(U &&expr) noexcept -> basic_eventually&

Store a value in the eventually, requires that empty() is true.

After this function is called, has_value() will be true.

template<typename U>
inline auto operator=(U &&expr) noexcept(std::is_nothrow_constructible_v<T, U>) -> basic_eventually&

Store a value in the eventually, requires that empty() is true.

After this function is called, has_value() will be true.

Public Members

impl::empty_t m_empty

impl::else_empty_t<Exception, std::exception_ptr> m_exception

impl::eventually_value_t<T> m_value