The Unexpected Fallout Of The Rail Mega Merger

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