ValueOrNone<T> - Boost.Outcome documentation

# `ValueOrNone<T>`

If on C++ 20 or the Concepts TS is enabled, a boolean concept matching types with a public `.has_value()` observer which returns `bool`, and a public `.value()` observer function.

If without Concepts, a static constexpr bool which is true for types matching the same requirements, using a SFINAE based emulation.

This concept matches optional-like types such as `std::optional<T>` . Note it also matches P0323 `std::expected<T, E>` , which also has an optional-like interface. You may thus wish to preferentially match `ValueOrError<T, E>` for any given `T`.

Namespace: `BOOST_OUTCOME_V2_NAMESPACE::convert`

Header: `<boost/outcome/convert.hpp>`

Last revised: December 13, 2018 at 17:36:11 UTC