The Unexpected Dual Nature Of Computer Design Are You Missing This

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· the class template std::unexpected represents an unexpected value stored in std::expected. · return value the previously-installed unexpected handler, or a null pointer value if none was installed. · 1) a tag type for in-place construction of an unexpected value in an std::expected object. · if *this contains an unexpected value, invokes f with the unexpected value of *this as the argument and returns its result. A program is ill-formed if it instantiates an unexpected with a non-object type, an array type, a specialization of … // specialization for void template class bad_expected_access ; 2) throws any exception thrown by the initialization of the expected or unexpected value. 1-4) the expected value is initialized with the expected value val of this. · synopsis // mostly freestanding namespace std { // class template unexpected template class unexpected; · 1) detects if the current thread has a live exception object, that is, an exception has been thrown or rethrown and not yet entered a matching catch clause, std::terminate or std::unexpected. In addition, t must not be std::in_place_t or std::unexpect_t. In other words, std::uncaught_exception detects if stack … Otherwise, error() can be used to access the unexpected value. // in-place construction of unexpected values struct unexpect_t · represents an expected void value or contains an unexpected value. If it contains an unexpected value, it is nested within the expected object. Otherwise, returns a std::expected object that represents an expected value. · std::unexpected() is called by the c++ runtime when a dynamic exception specification is violated: 2) a constant of type const std::unexpect_t which is usually directly passed to a constructor of std::expected to construct an unexpected value. If has_value() returns true, operator() can be used to access the expected value; · exceptions primary template constructors 1) throws any exception thrown by the initialization of the expected value. A program is ill-formed if it instantiates an expected with a reference type, a function type, or a specialization of std::unexpected. // class template bad_expected_access template class bad_expected_access; · return value has_val notes a std::expected object is never valueless. In either case, std::unexpected calls the currently installed std::unexpected. Std::unexpected() may also be called directly from the program. In particular, std::expected has constructors with std::unexpected as a single argument, which creates an expected object that contains an unexpected value. An exception is thrown from a function whose exception specification forbids exceptions of this type. 3) throws any exception thrown by the initialization of the expected or unexpected value.