Struct Extensions 

pub struct Extensions { /* private fields */ }

A typed map indexed by TypeId. Each T: Any + Send + Sync + 'static can have at most one value stored.

Implementations

impl Extensions

pub fn new() -> Self

Create an empty Extensions.

pub fn insert<T: Any + Send + Sync + 'static>(&mut self, value: T) -> Option<T>

Insert a value. Returns the previous value of the same type, if any.

pub fn get<T: Any + Send + Sync + 'static>(&self) -> Option<&T>

Get a reference to a stored value of type T.

pub fn get_mut<T: Any + Send + Sync + 'static>(&mut self) -> Option<&mut T>

Get a mutable reference to a stored value of type T.

pub fn remove<T: Any + Send + Sync + 'static>(&mut self) -> Option<T>

Remove and return the stored value of type T.

pub fn contains<T: Any + Send + Sync + 'static>(&self) -> bool

True if a value of type T is stored.

pub fn len(&self) -> usize

Number of distinct types stored.

pub fn is_empty(&self) -> bool

True if no values are stored.

pub fn clear(&mut self)

Clear all stored values.

Trait Implementations

impl Clone for Extensions

fn clone(&self) -> Self

Clones the map, but NOT the values inside. Cloning here makes a fresh empty Extensions — there’s no general way to clone arbitrary dyn Any. If you need cloned values, store Arc<T> instead of T.

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

Performs copy-assignment from source.

impl Debug for Extensions

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

Formats the value using the given formatter.

impl Default for Extensions

fn default() -> Extensions

Returns the “default value” for a type.

impl Serialize for Extensions

fn serialize<Se: Serializer>(&self, s: Se) -> Result<Se::Ok, Se::Error>

Serializes as an empty JSON object. Extensions contains type-erased runtime data that cannot be generically serialized; the empty-object representation satisfies S: Serialize bounds without losing any recoverable information.