Struct Lineage 

pub struct Lineage<T> { /* private fields */ }

A type of cell that allows replacing the contained value without invalidating references to the current value.

Implementations

impl<T> Lineage<T>

pub fn new(value: T) -> Self

Creates a new Lineage with the provided value.

pub fn get(&self) -> &T

Gets a reference to the current value.

pub fn get_mut(&mut self) -> &mut T

Gets a mutable reference to the current value.

Performs better than get but requires &mut self.

pub fn set(&self, value: T)

Replaces the value.

Replacing the value does not invalidate existing references to the previous value. The previous value is kept alive until you call clear or drop the Lineage. The new value is stored in a Box which causes a heap allocation.

pub fn set_mut(&mut self, value: T)

Replaces the value.

Performs much better than set but requires &mut self. Does not cause a heap allocation. The implementation is a more optimized version of the following:

fn set_mut<T>(lineage: &mut Lineage<T>, value: T) {
    lineage.clear();
    *lineage.get_mut() = value;
}

pub fn clear(&mut self)

Drops all past values. Does not affect the current value.

This can only be called if no references to any of the previous values exist anymore. This is ensured by the &mut self requirement. Should be called as often as possible to avoid having many past values kept alive unnecessarily.

pub fn drain(&mut self) -> impl Iterator<Item = T>

Same as clear but returns ownership of past values.

The values are iterated over from newest to oldest. The iterator can safely be dropped, all remaining values in the iterator will be dropped.

pub fn into_inner(self) -> T

Returns ownership of the current value.

Trait Implementations

impl<T> Clone for Lineage<T>

where T: Clone,

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<T> Debug for Lineage<T>

where T: Debug,

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

Formats the value using the given formatter.

impl<T> Default for Lineage<T>

where T: Default,

fn default() -> Self

Returns the “default value” for a type.

impl<T> From<T> for Lineage<T>

fn from(value: T) -> Self

Converts to this type from the input type.