mod_events/
core.rs

1//! Core event system traits and types
2
3use std::any::{Any, TypeId};
4use std::fmt;
5
6/// Core trait that all events must implement
7///
8/// This trait provides the foundation for type-safe event dispatch.
9/// All event types must implement this trait to be used with the dispatcher.
10///
11/// # Example
12///
13/// ```rust
14/// use mod_events::Event;
15///
16/// #[derive(Debug, Clone)]
17/// struct UserRegistered {
18///     user_id: u64,
19///     email: String,
20/// }
21///
22/// impl Event for UserRegistered {
23///     fn as_any(&self) -> &dyn std::any::Any {
24///         self
25///     }
26/// }
27/// ```
28pub trait Event: Any + Send + Sync + fmt::Debug {
29    /// Returns the event as [`Any`] for downcasting.
30    fn as_any(&self) -> &dyn Any;
31
32    /// Returns the unique [`TypeId`] identifier for this event type.
33    ///
34    /// Equivalent to `<Self as Any>::type_id(self)` since `Event`
35    /// requires the [`Any`] supertrait. Both methods are available and
36    /// return identical values; this one is provided for ergonomics
37    /// when working with `&dyn Event` trait objects, where the
38    /// supertrait method requires a `&dyn Any` cast first.
39    fn type_id(&self) -> TypeId {
40        TypeId::of::<Self>()
41    }
42
43    /// Returns the event name for debugging / logging.
44    ///
45    /// Backed by [`std::any::type_name`]. The exact format is
46    /// **not stable** across compiler versions — the Rust standard
47    /// library reserves the right to change `type_name` output
48    /// between releases. Treat the result as opaque human-readable
49    /// text. Do not parse it, persist it, or use it as a stable
50    /// cross-process identifier; use [`Event::type_id`] for that
51    /// instead.
52    fn event_name(&self) -> &'static str {
53        std::any::type_name::<Self>()
54    }
55}
56
57/// Unique identifier for event listeners
58///
59/// This is returned when subscribing to events and can be used
60/// to unsubscribe specific listeners later.
61#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
62pub struct ListenerId {
63    pub(crate) id: usize,
64    pub(crate) type_id: TypeId,
65}
66
67impl ListenerId {
68    pub(crate) fn new(id: usize, type_id: TypeId) -> Self {
69        Self { id, type_id }
70    }
71}
mod_events/core.rs

mod_events/
core.rs
