Struct Extensions 

pub struct Extensions { /* private fields */ }

Type-safe container for injecting custom state into handlers.

Extensions allow pre-dispatch hooks to inject state that handlers can retrieve. This enables dependency injection without modifying handler signatures.

Warning: Clone Behavior

Extensions is not cloned when the container is cloned. Cloning an Extensions instance results in a new, empty map. This is because the underlying Box<dyn Any> values cannot be cloned generically.

If you need to share state across threads/clones, use Arc<T> inside the extension.

Example

use standout_dispatch::{Extensions, CommandContext};

// Define your state types
struct ApiClient { base_url: String }
struct UserScope { user_id: u64 }

// In a pre-dispatch hook, inject state
let mut ctx = CommandContext::default();
ctx.extensions.insert(ApiClient { base_url: "https://api.example.com".into() });
ctx.extensions.insert(UserScope { user_id: 42 });

// In a handler, retrieve state
let api = ctx.extensions.get_required::<ApiClient>()?;
println!("API base: {}", api.base_url);

Implementations

impl Extensions

pub fn new() -> Self

Creates a new empty extensions container.

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

Inserts a value into the extensions.

If a value of this type already exists, it is replaced and returned.

pub fn get<T: 'static>(&self) -> Option<&T>

Gets a reference to a value of the specified type.

Returns None if no value of this type exists.

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

Gets a mutable reference to a value of the specified type.

Returns None if no value of this type exists.

pub fn get_required<T: 'static>(&self) -> Result<&T, Error>

Gets a required reference to a value of the specified type.

Returns an error if no value of this type exists.

pub fn get_mut_required<T: 'static>(&mut self) -> Result<&mut T, Error>

Gets a required mutable reference to a value of the specified type.

Returns an error if no value of this type exists.

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

Removes a value of the specified type, returning it if it existed.

pub fn contains<T: 'static>(&self) -> bool

Returns true if the extensions contain a value of the specified type.

pub fn len(&self) -> usize

Returns the number of extensions stored.

pub fn is_empty(&self) -> bool

Returns true if no extensions are stored.

pub fn clear(&mut self)

Removes all extensions.

Trait Implementations

impl Clone for Extensions

fn clone(&self) -> Self

Returns a duplicate of the value.

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.