Enum StatedInstants 

#[non_exhaustive]
pub enum StatedInstants {
    Valid(String),
    Recorded(String),
    Both {
        valid: String,
        recorded: String,
    },
}

Which instants a traversal stated, for the one error that has to name them (0.13.10, W7.7, D-183).

Three cases and never zero. DbError::AttributeModeUnstated exists because an instant was set, so a fourth case carrying neither would be a state no construction site can reach — D-177’s objection to a Result that cannot fail, in a different shape. Self::new returns an Option and the None is the ordinary live traversal, resolved before any error exists.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

Valid(String)

as_of_valid alone — what was true then.

Recorded(String)

as_of_recorded alone — what we believed then.

Both

Both, which is the bitemporal cell: what did we believe at recorded about what was true at valid.

Fields

valid: String

The valid-time instant.

recorded: String

The transaction-time instant.

Implementations

impl StatedInstants

pub fn new(valid: Option<&str>, recorded: Option<&str>) -> Option<Self>

None when neither axis was set, which is not an error and not this type’s business to describe.

pub fn valid(&self) -> Option<&str>

The valid-time instant, if this traversal stated one.

pub fn recorded(&self) -> Option<&str>

The transaction-time instant, if this traversal stated one.

Trait Implementations

impl Clone for StatedInstants

fn clone(&self) -> StatedInstants

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for StatedInstants

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for StatedInstants

Rendered as the calls that produce them, which is the whole point.

A message reading as_of(2020-06-01) names a method that has not existed since 0.12.17 (D-174), so a caller who goes looking for it finds nothing — and, worse, is not told which of the two axes the instant they set landed on. as_of_valid(…) and as_of_recorded(…) are what a caller typed and what a caller can change.

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for StatedInstants

impl PartialEq for StatedInstants

fn eq(&self, other: &StatedInstants) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for StatedInstants