22 General utilities library [utilities]

22.8 Expected objects [expected]

22.8.4 Class template bad_expected_access [expected.bad]

namespace std { template<class E> class bad_expected_access : public bad_expected_access<void> { public: explicit bad_expected_access(E); const char* what() const noexcept override; E& error() & noexcept; const E& error() const & noexcept; E&& error() && noexcept; const E&& error() const && noexcept; private: E unex; // exposition only }; }

The class template bad_expected_access defines the type of objects thrown as exceptions to report the situation where an attempt is made to access the value of an expected<T, E> object for which has_value() is false.

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explicit bad_expected_access(E e);

Effects: Initializes unex with std::move(e).

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

Returns: unex.

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

Returns: std::move(unex).

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const char* what() const noexcept override;

Returns: An implementation-defined ntbs.