Struct Extensions 

pub struct Extensions { /* private fields */ }

A type-safe, thread-safe container for storing arbitrary types.

This structure allows storing multiple values of different types in a single container, with type-safe retrieval. Values are stored wrapped in Arc for efficient cloning.

Extensions are used at three levels in Zel RPC:

• Server Extensions: Shared across all connections (e.g., database pools)
• Connection Extensions: Scoped to a single connection (e.g., authentication sessions)
• Request Extensions: Unique per request (e.g., trace IDs)

Implementations

impl Extensions

pub fn new() -> Self

Create a new, empty Extensions container.

pub fn with<T: Send + Sync + 'static>(self, value: T) -> Self

Add a value to the extensions, returning a new Extensions instance.

This method creates a new Extensions instance with the added value, leaving the original unchanged. This is useful for building up extensions in a builder-style pattern.

Values are stored by their TypeId, so each type can only be stored once. Adding a value of a type that already exists will replace the previous value.

CRITICAL: This method correctly clones the HashMap contents, not just the Arc pointer. Using (*self.map).clone() ensures we get a new HashMap with cloned Arc pointers to the values, rather than just cloning the outer Arc.

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

Retrieve a value from the extensions by type.

Returns None if no value of the specified type exists.

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

Check if a value of the specified type exists in the extensions.

pub fn get_or_else<T, F>(&self, default: F) -> Arc<T>

where T: Send + Sync + 'static, F: FnOnce() -> T,

Retrieve a value from the extensions, or provide a default if it doesn’t exist.

Trait Implementations

impl Clone for Extensions

fn clone(&self) -> Extensions

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.