ferroui_dynamic_data/binding/
abstract_notify_property_changed.rs

1//! `AbstractNotifyPropertyChanged` (`Binding/AbstractNotifyPropertyChanged.cs`): the base of the
2//! objects that raise `PropertyChanged`, as a part that a type embeds.
3
4use ferroui_reactive::disposables::Disposable;
5use ferroui_system::component_model::INotifyPropertyChanged;
6use ferroui_system::events::Event;
7use ferroui_system::IDisposable;
8use std::cell::Cell;
9use std::fmt;
10use std::rc::Rc;
11
12/// A backing field that [`AbstractNotifyPropertyChanged::set_and_raise`] reads and assigns: a
13/// `Cell` for a value that is `Copy`, a `RefCell` for the others (`ref T backingField`). It is
14/// `ferroui-system`'s, which the reactive objects of `ferroui-reactiveui` share.
15pub use ferroui_system::component_model::BackingField;
16
17struct Inner {
18    property_changed: Event<str>,
19    is_suspended: Cell<bool>,
20}
21
22/// The base of an object that notifies the changes of its properties
23/// (`AbstractNotifyPropertyChanged`).
24///
25/// Deviation (DEVIATIONS.md, DynamicData): upstream's abstract class is a part that a type embeds;
26/// the type implements `INotifyPropertyChanged` by returning [`property_changed`](Self::property_changed),
27/// and its setters call [`set_and_raise`](Self::set_and_raise) with the property name that
28/// `[CallerMemberName]` gives upstream (the PascalCase name of the getter, which `prop!` derives).
29///
30/// ```
31/// use ferroui_dynamic_data::binding::AbstractNotifyPropertyChanged;
32/// use ferroui_system::component_model::INotifyPropertyChanged;
33/// use ferroui_system::events::Event;
34/// use std::cell::Cell;
35///
36/// #[derive(Default)]
37/// struct Item { notify: AbstractNotifyPropertyChanged, age: Cell<i32> }
38/// impl Item {
39///     fn age(&self) -> i32 { self.age.get() }
40///     fn set_age(&self, value: i32) { self.notify.set_and_raise(&self.age, value, "Age") }
41/// }
42/// impl INotifyPropertyChanged for Item {
43///     fn property_changed(&self) -> &Event<str> { self.notify.property_changed() }
44/// }
45///
46/// let item = Item::default();
47/// item.set_age(3);
48/// assert_eq!(item.age(), 3);
49/// ```
50pub struct AbstractNotifyPropertyChanged {
51    inner: Rc<Inner>,
52}
53
54impl Default for AbstractNotifyPropertyChanged {
55    fn default() -> Self {
56        Self::new()
57    }
58}
59
60impl fmt::Debug for AbstractNotifyPropertyChanged {
61    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
62        f.debug_struct("AbstractNotifyPropertyChanged")
63            .field("handlers", &self.inner.property_changed.handler_count())
64            .field("is_suspended", &self.inner.is_suspended.get())
65            .finish()
66    }
67}
68
69impl AbstractNotifyPropertyChanged {
70    /// A part without handlers.
71    pub fn new() -> Self {
72        Self { inner: Rc::new(Inner { property_changed: Event::new(), is_suspended: Cell::new(false) }) }
73    }
74
75    /// The event raised when a property value has changed (`PropertyChanged`).
76    pub fn property_changed(&self) -> &Event<str> {
77        &self.inner.property_changed
78    }
79
80    /// Raises `PropertyChanged` for `property_name`; an empty name means every property
81    /// (`OnPropertyChanged(string? propertyName)`, where `null` is every property). Nothing is
82    /// raised while the notifications are suspended.
83    pub fn on_property_changed(&self, property_name: &str) {
84        Self::raise(&self.inner, property_name);
85    }
86
87    fn raise(inner: &Inner, property_name: &str) {
88        if inner.is_suspended.get() {
89            return;
90        }
91        inner.property_changed.raise(property_name);
92    }
93
94    /// Assigns `value` to `field` and raises `PropertyChanged` for `property_name`, unless the
95    /// field already holds an equal value (`SetAndRaise<T>(ref T, T, string?)`).
96    pub fn set_and_raise<T: PartialEq>(&self, field: &impl BackingField<T>, value: T, property_name: &str) {
97        self.set_and_raise_with(field, value, |current, value| current == value, property_name);
98    }
99
100    /// [`set_and_raise`](Self::set_and_raise) with an equality comparer
101    /// (`SetAndRaise<T>(ref T, T, IEqualityComparer<T>?, string?)`).
102    pub fn set_and_raise_with<T>(&self, field: &impl BackingField<T>, value: T, comparer: impl Fn(&T, &T) -> bool, property_name: &str) {
103        if field.equals(&value, &comparer) {
104            return;
105        }
106        field.store(value);
107        self.on_property_changed(property_name);
108    }
109
110    /// Suspends the notifications until the result is disposed; then, when
111    /// `invoke_property_changed_event_when_finished` is true, raises `PropertyChanged` for every
112    /// property (`SuspendNotifications(bool invokePropertyChangeEventWhenDisposed = true)`).
113    ///
114    /// Deviation (DEVIATIONS.md, DynamicData): the reference checkout no longer has this member;
115    /// the earlier API marked it obsolete ("This never worked properly in the first place"). It is
116    /// ported from that API: the suspension is one flag, so the first disposal of nested
117    /// suspensions ends it.
118    pub fn suspend_notifications(&self, invoke_property_changed_event_when_finished: bool) -> Rc<dyn IDisposable> {
119        self.inner.is_suspended.set(true);
120        let inner = self.inner.clone();
121        Disposable::create(move || {
122            inner.is_suspended.set(false);
123            if invoke_property_changed_event_when_finished {
124                Self::raise(&inner, "");
125            }
126        })
127    }
128}
129
130impl INotifyPropertyChanged for AbstractNotifyPropertyChanged {
131    fn property_changed(&self) -> &Event<str> {
132        &self.inner.property_changed
133    }
134}
ferroui_dynamic_data/binding/abstract_notify_property_changed.rs

ferroui_dynamic_data/binding/
abstract_notify_property_changed.rs
