Struct design_pattern_examples_rust::observer::observer_numberproducer::ObserverNumberProducer

pub struct ObserverNumberProducer {
    number: u32,
    observers: Vec<Rc<RefCell<dyn IObserverNumberChanged>>>,
}

Represents the Observer Subject in this example, in this case, a struct that contains a single number that is updated with a call to the update() method. Whenever update() is called, the number is incremented and all observers are notified. The observers are passed (“pushed”) the changed number through the IObserverNumberChanged trait.

Fields

number: u32

The number being maintained.

observers: Vec<Rc<RefCell<dyn IObserverNumberChanged>>>

The list of observers subscribed to this class instance.

Implementations

impl ObserverNumberProducer

pub fn new() -> ObserverNumberProducer

Default constructor

pub fn add_observer( &mut self, observer: &Rc<RefCell<dyn IObserverNumberChanged>> )

Call this method to subscribe an observer to this struct for notifications about changing numbers. Does nothing if the given observer is already subscribed.

Parameters

• observer

  The observer as represented by the IObserverNumberChanged trait.

pub fn remove_observer( &mut self, observer: &Rc<RefCell<dyn IObserverNumberChanged>> )

Call this method to unsubscribe an observer from this struct so notifications are no longer received. Does nothing if the given observer was not subscribed.

Parameters

• observer

  The observer as represented by the IObserverNumberChanged trait.

pub fn update(&mut self)

Update the number then notify all observers.

fn find_index_of_observer( &self, observer: &Rc<RefCell<dyn IObserverNumberChanged>> ) -> Option<usize>

Helper method to retrieve the index to the specified observer if the observer is in the list.

Parameters

• observer

  The observer as represented by the IObserverNumberChanged trait.

Returns

Returns Some(index) if the observer was found; otherwise, returns None.

fn notify_observers(&self)

Helper method to notify all observers that the number has changed.