Module core::optionStable
[-] [+]
[src]
Optional values
Type Option
represents an optional value: every Option
is either Some
and contains a value, or None
, and
does not. Option
types are very common in Rust code, as
they have a number of uses:
- Initial values
- Return values for functions that are not defined over their entire input range (partial functions)
- Return value for otherwise reporting simple errors, where
None
is returned on error - Optional struct fields
- Struct fields that can be loaned or "taken"
- Optional function arguments
- Nullable pointers
- Swapping things out of difficult situations
Options are commonly paired with pattern matching to query the presence
of a value and take action, always accounting for the None
case.