Struct Expando

pub struct Expando { /* private fields */ }

A lazy collection of values of every type.

An Expando contains a single instance of every type. The values are instantiated lazily when accessed. Useful for letting modules add their own state to context objects without requiring the context object itself to know about the types in every module.

Typically the type a module uses in the Expando will be private to that module, which lets the module know that no other code is accessing its slot on the expando.

Implementations

impl Expando

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

Get the slot in the expando associated with the given type.

The slot is added to the expando lazily but the same instance is returned every time the expando is queried for the same type.

pub fn get_or_init<T: Any + Send + Sync + 'static>( &self, init: impl FnOnce() -> T, ) -> Arc<T>

Get the slot in the expando associated with the given type, running init to initialize the slot if needed.

The slot is added to the expando lazily but the same instance is returned every time the expando is queried for the same type.

pub fn get_or_try_init<T: Any + Send + Sync + 'static, E>( &self, try_init: impl FnOnce() -> Result<T, E>, ) -> Result<Arc<T>, E>

Get the slot in the expando associated with the given type, running try_init to initialize the slot if needed. Returns an error only if try_init returns an error.

The slot is added to the expando lazily but the same instance is returned every time the expando is queried for the same type.

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

Get the slot in the expando associated with the given type if it has previously been initialized.

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

Remove the provided type from the expando if it is present.

Trait Implementations

impl Debug for Expando

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

Formats the value using the given formatter.

impl Default for Expando

fn default() -> Expando

Returns the “default value” for a type.