Optional

template <typename T>
class Optional

This class encapsulates values which can be tested for null-ness.

Public Functions

Optional()

Constructor of an empty instance.

Optional(const T &value)

Constructor.

AMPL_EXPLICIT operator bool() const

The cast to bool returns true if the instance has a value, false otherwise.

const T &operator*() const

Accesses the contained value, returns a reference to the contained value.

The behaviour is undefined if the object does not contain a value.

const T *operator->() const

Accesses the contained value, returns a pointer to the contained value.

The behaviour is undefined if the object does not contain a value.

const T &value() const

Accesses the contained value, returns a reference to the contained value.

Exceptions

• std::runtime_error: if the object does not contain a value