roopes_core/patterns/observer/
mod.rs

1//!
2#![cfg_attr(feature = "doc-images",
3  cfg_attr(
4    all(),
5    doc = ::embed_doc_image::embed_image!(
6        "observer-diagram",
7        "src/patterns/observer/observer.svg"
8)))]
9//! Contains types which implement the "Observer"
10//! pattern, in which a single object is used to
11//! delegate notifications to a group of dynamic
12//! listening object.
13//!
14//! ![observer diagram][observer-diagram]
15
16pub mod hash_subject;
17pub mod vec_subject;
18
19use crate::prelude::*;
20pub use hash_subject::HashSubject;
21pub use vec_subject::VecSubject;
22
23#[cfg(test)]
24mod tests;
25
26/// An object which notifies some group of
27/// [`Observer`]s.  When it is notified,
28/// all the listeners are notified.
29pub trait Subject
30{
31    /// Triggers the [`Observer`]s corresponding
32    /// `notify` implementations.
33    fn notify(&self);
34}
35
36/// An object notified by a [`Subject`].
37pub trait Observer
38{
39    /// Executes some arbitrary block in the
40    /// implementing object.
41    fn notify(&self);
42}
43
44/// Allows [`Observer`]s to be added to the
45/// implementing [`Subject`].
46pub trait AttachableSubject<O>: Subject
47where
48    O: Observer,
49{
50    /// Adds the [`Observer`] to the list of
51    /// elements notified when the [`Subject`]
52    /// is notified.
53    fn attach(
54        &mut self,
55        attach_observer: O,
56    );
57}
58
59/// Allows [`Observer`]s to be removed from the
60/// implementing [`Subject`].
61pub trait DetachableSubject<O, E>: Subject
62where
63    O: Observer,
64{
65    /// Detaches the given [`Observer`] from the
66    /// [`Subject`] so it would no
67    /// longer receive notifications.
68    ///
69    /// # Errors
70    /// E: The error that occurred during
71    /// detachment.
72    fn detach(
73        &mut self,
74        detach_observer: &O,
75    ) -> Result<(), E>;
76}
77
78/// Exposes the [`Observer`] and [`Subject`] types
79/// at the library level.
80pub mod prelude
81{
82    pub use super::{
83        AttachableSubject,
84        DetachableSubject,
85        Observer,
86        Subject,
87    };
88}
roopes_core/patterns/observer/mod.rs

roopes_core/patterns/observer/
mod.rs
