Struct Extensions 

pub struct Extensions { /* private fields */ }

A type-erased container for app-specific state.

Extensions lets applications attach arbitrary typed values to AppState without modifying the framework. Each type can appear at most once — the type itself is the key.

Examples

use atrg_core::Extensions;

struct S3Client { bucket: String }
struct SmtpConfig { host: String }

let mut ext = Extensions::new();
ext.insert(S3Client { bucket: "my-blobs".into() });
ext.insert(SmtpConfig { host: "smtp.example.com".into() });

assert_eq!(ext.get::<S3Client>().expect("registered").bucket, "my-blobs");
assert_eq!(ext.get::<SmtpConfig>().expect("registered").host, "smtp.example.com");
assert!(ext.get::<u64>().is_none());

Implementations

impl Extensions

pub fn new() -> Self

Create a new, empty extensions map.

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

Insert a value into the map. If a value of this type already exists, it is replaced and the old value is returned.

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

Retrieve a reference to a value by type. Returns None if the type has not been inserted.

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

Returns true if the map contains a value of the given type.

pub fn len(&self) -> usize

Returns the number of entries in the map.

pub fn is_empty(&self) -> bool

Returns true if the map is empty.

Trait Implementations

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.