Boost
C++ Libraries
...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
This library allows the template parameter T
to be of reference type: T&, and to some extent, T
const&.
However, since references are not real objects some restrictions apply and some operations are not available in this case:
Also, even though optional<T&>
treats it wrapped pseudo-object much as a real value, a true real reference
is stored so aliasing will ocurr:
optional<T&>
will copy the references but all these references will nonetheless reefer
to the same object.