AlinSpace.Optional 1.0.3

AlinSpace.Optional

AlinSpace Optional Types.

Why?

In C# reference types can either point to an object (be not "null") or not point to any object (be "null"). Value types can't be "null".

However, both reference and value types can be "default". But "default" does not mean the same for reference and value types. For reference types it means "null" and for value types it means the default value (e.g. for integer it is 0).

Optionals help with this problem, by making both reference and value types behave the same.

Examples

The following optional contains the value 5:

Optional<int> optional = Optional<int>.Some(5);

// Same as above.
Optional<int> optional = 5;

optional.HasValue // true
optional.HasNoValue // false
optional.Value // 5
optional.ValueOrDefault // 5

The following optional contains no value:

Optional<int> optional = Optional<int>.None();

optional.HasValue // false
optional.HasNoValue // true
optional.Value // throws OptionalHasNoValueException
optional.ValueOrDefault // 0

However be careful about "default". The optional will have a value:

Optional<int> optional = default;

optional.HasValue // true
optional.HasNoValue // false
optional.Value // 0
optional.ValueOrDefault // 0