Implementation

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Implementation

Class: Observer.

Constants
OBSERVABLE private
An observable type Set. All type identifiers with corresponding Observers.
Attributes
Methods
Observer.observable()
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  def Observer.observable()
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    return OBSERVABLE
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  end
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Gets OBSERVABLE. Returns the Set reference.
Observer.type(identifier = nil)
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  def Observer.type(identifier = nil)
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    return observable().include?(identifier)
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  end
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Predicate. Verifies an identifier is an observable identifier. Takes an argument identifier. Expects any identifier. Returns true in the case the argument is an observable type. Returns false otherwise.
Observer.changed(instance = nil)
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  def Observer.changed(instance = nil)
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    unless (type(instance.class()))
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      return false
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    else
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​
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      k_o   = kind_observer(instance)
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      k_o_i = k_o.instance()
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      case
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      when k_o.equal?(NodeObserver)
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        return (k_o_i.subject(instance) && k_o_i.changed_node(instance))
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      end
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​
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    end
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​
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  end
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Predicate. Verifies an instance's state. Takes an argument, instance. Expects any instance type. Returns true in the case the argument is an observable type, it is an Observer's subject, and its state changed. Returns false otherwise.
Observer.add_subject(subject = nil)
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  def Observer.add_subject(subject = nil)
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​
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    k_o   = kind_observer(subject)
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    k_o_i = k_o.instance()
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    k_o_i.add(subject)
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    return nil
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​
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  end
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Adds a subject in the appropriate Observer. Takes an observable instance argument, subject. Adds the argument in the corresponding Observer's changed Set. Returns nil.
Observer.remove_subject(subject = nil)
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  def Observer.remove_subject(subject = nil)
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​
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    k_o   = kind_observer(subject)
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    k_o_i = k_o.instance()
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    k_o_i.remove(subject)
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    return nil
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​
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  end
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Removes a subject in the appropriate Observer. Takes an observable instance argument, subject. Removes the element from its changed Set. Returns nil.
Observer.notify(instance = nil)
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  def Observer.notify(instance = nil)
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​
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    ic_identifier = instance.class()
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    if (type(ic_identifier))
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​
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      k_o = kind_observer(instance)
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      k_o.subject_changed(instance)
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      return nil
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​
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    else
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      raise(ArgumentError, "#{instance} is not an observable instance.")
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    end
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​
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  end
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Notifies the appropriate Observer kind an instance's state changed. Takes an observable instance argument, instance. Returns nil. Raises an ArgumentError in the case the argument is not an observable instance.
Observer.kind_observer(instance = nil) private
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  def Observer.kind_observer(instance = nil)
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​
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    ic_identifier = instance.class()
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    case
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    when ic_identifier.equal?(Node)
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      return NodeObserver
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    else
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      raise(ArgumentError, "#{instance} is not an observable instance.")
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    end
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​
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  end
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Gets the corresponding type's Observer. Takes an argument, instance. Expects observable instances. In the case the instance's class is an observable type, returns its corresponding Observer. Otherwise, raises an ArgumentError.
Observable.new() private, undefined