Struct Durability

pub struct Durability(/* private fields */);

Describes how likely a value is to change – how “durable” it is. By default, inputs have Durability::LOW and interned values have Durability::HIGH. But inputs can be explicitly set with other durabilities.

We use durabilities to optimize the work of “revalidating” a query after some input has changed. Ordinarily, in a new revision, queries have to trace all their inputs back to the base inputs to determine if any of those inputs have changed. But if we know that the only changes were to inputs of low durability (the common case), and we know that the query only used inputs of medium durability or higher, then we can skip that enumeration.

Typically, one assigns low durabilities to inputs that the user is frequently editing. Medium or high durabilities are used for configuration, the source from library crates, or other things that are unlikely to be edited.

Implementations

impl Durability

pub const LOW: Durability

Low durability: things that change frequently.

Example: part of the crate being edited

pub const MEDIUM: Durability

Medium durability: things that change sometimes, but rarely.

Example: a Cargo.toml file

pub const HIGH: Durability

High durability: things that are not expected to change under common usage.

Example: the standard library or something from crates.io

Trait Implementations

impl Clone for Durability

fn clone(&self) -> Durability

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for Durability

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

Formats the value using the given formatter.

impl Ord for Durability

fn cmp(&self, other: &Durability) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl PartialEq for Durability

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialOrd for Durability

fn partial_cmp(&self, other: &Durability) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

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

Tests less than (for self and other) and is used by the < operator.

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

Tests less than or equal to (for self and other) and is used by the <= operator.

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

Tests greater than (for self and other) and is used by the > operator.

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

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl Copy for Durability

impl Eq for Durability

impl StructuralPartialEq for Durability