Struct Cached

pub struct Cached<K: PartialEq + Clone, V> {
    contents: Option<(K, V)>,
}

Store a cached key/value pair, only recalculating when the key changes.

Fields

contents: Option<(K, V)>

Implementations

impl<K: PartialEq + Clone, V> Cached<K, V>

pub fn new() -> Cached<K, V>

pub fn key(&self) -> Option<K>

Get the current key.

pub fn value(&self) -> Option<&V>

Get the current value.

pub fn value_mut(&mut self) -> Option<&mut V>

Get the current value, mutably.

pub fn update<F: FnMut(K) -> V>(&mut self, key: Option<K>, produce_value: F)

Update the value if the key has changed.

pub fn set(&mut self, key: K, value: V)

update is preferred, but sometimes produce_value needs to borrow the same struct that owns this Cached. In that case, the caller can manually check key and call this.

pub fn clear(&mut self)

pub fn take(&mut self) -> Option<(K, V)>

Clears the current pair and returns it.

Trait Implementations

impl<K: PartialEq + Clone, V> Default for Cached<K, V>

fn default() -> Self

Returns the “default value” for a type.