cppdraft_translate/cppdraft/expected/void/obs.md

[expected.void.obs]

22 General utilities library [utilities]

22.8 Expected objects [expected]

22.8.7 Partial specialization of expected for void types [expected.void]

22.8.7.6 Observers [expected.void.obs]

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constexpr explicit operator bool() const noexcept; constexpr bool has_value() const noexcept;

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Returns: has_val.

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constexpr void operator*() const noexcept;

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Hardened preconditions: has_value() is true.

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constexpr void value() const &;

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Mandates: is_copy_constructible_v is true.

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Throws: bad_expected_access(error()) if has_value() is false.

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constexpr void value() &&;

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Mandates: is_copy_constructible_v is true andis_move_constructible_v is true.

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Throws: bad_expected_access(std​::​move(error())) if has_value() is false.

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constexpr const E& error() const & noexcept; constexpr E& error() & noexcept;

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Hardened preconditions: has_value() is false.

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Returns: unex.

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constexpr E&& error() && noexcept; constexpr const E&& error() const && noexcept;

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Hardened preconditions: has_value() is false.

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Returns: std​::​move(unex).

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template<class G = E> constexpr E error_or(G&& e) const &;

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Mandates: is_copy_constructible_v is true andis_convertible_v<G, E> is true.

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Returns: std​::​forward(e) if has_value() is true,error() otherwise.

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template<class G = E> constexpr E error_or(G&& e) &&;

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Mandates: is_move_constructible_v is true andis_convertible_v<G, E> is true.

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Returns: std​::​forward(e) if has_value() is true,std​::​move(error()) otherwise.