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OBSERVER PATTERN - Coggle Diagram

- - - - Object A is responsible to tell other subscribers that it's changed.
        
        How?
        
        Before pushing all the objects interested in the subject need to register.
        
        Observable (sends data to observers)
        
        Observers (subscribe)
    - - Object B checks every time if Object A has new data
        
        NOTE: if we have multiple objects it is not a good idea to use POL
- - - - ConcreteObservable
        
        Add(IObserver o)
        
        Remove(IObserver o)
        
        Notify()
        
        GetState()
        
        Dose 2 things:
        
        Observer stuff
        
        GetState
        
        Breaking single responsibility
  - - - ConcreteObserver
        
        Update()
        
        (ConcreteObserver)
        HAS A (ConcreteObservable) #
        
        Concretion has a relationship with concretion
        
        Usually we want to have dependencies between abstraction (Interfaces) not concretion
        
        When we construct the OBSERVER we pass the OBSERVABLE through the constructor so we can read data from it
        
        Example
        new ConcreteObserver(observable);