Module: ObservableArray

Includes:
Observable
Defined in:
lib/command_handlers/models/observable_array.rb

Overview

TODO prefix utility methods with double-underscore

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.extend_object(array) ⇒ Object 



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# File 'lib/command_handlers/models/observable_array.rb', line 43

def self.extend_object(array)
  array.instance_eval("alias __original_add <<")
  array.instance_eval <<-end_eval, __FILE__, __LINE__
    def <<(value)
      self.__original_add(value)
      notify_observers
    end
  end_eval

  array.instance_eval("alias __original_set_value []=")
  array.instance_eval <<-end_eval, __FILE__, __LINE__
    def []=(index, value)
      old_value = self[index]
      unregister_dependent_observers(old_value)
      self.__original_set_value(index, value)
      notify_observers
    end
  end_eval

  array.instance_eval("alias __original_delete delete")
  array.instance_eval <<-end_eval, __FILE__, __LINE__
    def delete(value)
      unregister_dependent_observers(value)
      self.__original_delete(value)
      notify_observers
    end
  end_eval

  array.instance_eval("alias __original_delete_at delete_at")
  array.instance_eval <<-end_eval, __FILE__, __LINE__
    def delete_at(index)
      old_value = self[index]
      unregister_dependent_observers(old_value)
      self.__original_delete_at(index)
      notify_observers
    end
  end_eval

  array.instance_eval("alias __original_clear clear")
  array.instance_eval <<-end_eval, __FILE__, __LINE__
    def clear
      each do |old_value|
        unregister_dependent_observers(old_value)
      end
      self.__original_clear
      notify_observers
    end
  end_eval

  super
end

Instance Method Details

#add_observer(observer, element_properties = nil) ⇒ Object 



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# File 'lib/command_handlers/models/observable_array.rb', line 9

def add_observer(observer, element_properties=nil)
  property_observer_list << observer
  [element_properties].flatten.compact.each do |property|
    each do |element|
      element.extend(ObservableModel) unless element.is_a?(ObservableModel)
      observer.observe(element, property)
    end
  end
  observer
end

#has_observer?(observer) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/command_handlers/models/observable_array.rb', line 31

def has_observer?(observer)
  property_observer_list.include?(observer)
end

#notify_observers ⇒ Object 



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# File 'lib/command_handlers/models/observable_array.rb', line 39

def notify_observers
  property_observer_list.each {|observer| observer.update}
end

#property_observer_list ⇒ Object 



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# File 'lib/command_handlers/models/observable_array.rb', line 35

def property_observer_list
  @property_observer_list ||= Set.new
end

#remove_observer(observer, element_properties = nil) ⇒ Object 



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# File 'lib/command_handlers/models/observable_array.rb', line 20

def remove_observer(observer, element_properties=nil)
  property_observer_list.delete(observer)
  [element_properties].flatten.compact.each do |property|
    each do |element|
      element.extend(ObservableModel) unless element.is_a?(ObservableModel)
      observer.unobserve(element, property)
    end
  end
  observer
end

#unregister_dependent_observers(old_value) ⇒ Object 



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# File 'lib/command_handlers/models/observable_array.rb', line 95

def unregister_dependent_observers(old_value)
  # TODO look into optimizing this
  return unless old_value.is_a?(ObservableModel) || old_value.is_a?(ObservableArray)
  property_observer_list.each do |observer|
    observer.unregister_dependents_with_observable([self, nil], old_value)
  end
end