Module: ObservableModel

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

Overview

TODO prefix utility methods with double-underscore

Defined Under Namespace

Classes: Updater

Instance Method Summary collapse

Instance Method Details

#add_observer(observer, property_name) ⇒ Object 



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# File 'lib/command_handlers/models/observable_model.rb', line 21

def add_observer(observer, property_name)
  return observer if has_observer?(observer, property_name)
  property_observer_list(property_name) << observer
  add_property_writer_observers(property_name)
  observer
end

#add_property_writer_observers(property_name) ⇒ Object

TODO upon updating values, make sure dependent observers are cleared (not added as dependents here)



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# File 'lib/command_handlers/models/observable_model.rb', line 55

def add_property_writer_observers(property_name)
  property_writer_name = "#{property_name}="
  method(property_writer_name)
  ensure_array_object_observer(property_name, send(property_name))
  begin
    method("__original_#{property_writer_name}")
  rescue
    instance_eval "alias __original_#{property_writer_name} #{property_writer_name}"
    instance_eval "      def \#{property_writer_name}(value)\n        old_value = self.\#{property_name}\n        unregister_dependent_observers('\#{property_name}', old_value)\n        self.__original_\#{property_writer_name}(value)\n        notify_observers('\#{property_name}')\n        ensure_array_object_observer('\#{property_name}', value, old_value)\n      end\n    end_eval\n  end\nrescue => e\n  # ignore writing if no property writer exists\n  Glimmer.logger.debug \"No need to observe property writer: \#{property_writer_name}\\n\#{e.message}\\n\#{e.backtrace.join(\"\\n\")}\"\nend\n", __FILE__, __LINE__

#array_object_observer_for(property_name) ⇒ Object 



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# File 'lib/command_handlers/models/observable_model.rb', line 96

def array_object_observer_for(property_name)
  @array_object_observers ||= {}
  unless @array_object_observers.has_key?(property_name)
    @array_object_observers[property_name] = ObservableModel::Updater.new(self, property_name)
  end
  @array_object_observers[property_name]
end

#ensure_array_object_observer(property_name, object, old_object = nil) ⇒ Object 



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# File 'lib/command_handlers/models/observable_model.rb', line 86

def ensure_array_object_observer(property_name, object, old_object = nil)
  return unless object.is_a?(Array)
  array_object_observer = array_object_observer_for(property_name)
  array_object_observer.observe(object)
  property_observer_list(property_name).each do |observer|
    observer.add_dependent([self, property_name] => [array_object_observer, object, nil])
  end
  array_object_observer_for(property_name).unregister(old_object) if old_object.is_a?(ObservableArray)
end

#has_observer?(observer, property_name) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/command_handlers/models/observable_model.rb', line 32

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

#has_observer_for_any_property?(observer) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/command_handlers/models/observable_model.rb', line 36

def has_observer_for_any_property?(observer)
  property_observer_hash.values.map(&:to_a).sum.include?(observer)
end

#notify_observers(property_name) ⇒ Object 



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# File 'lib/command_handlers/models/observable_model.rb', line 50

def notify_observers(property_name)
  property_observer_list(property_name).each {|observer| observer.update(send(property_name))}
end

#property_observer_hash ⇒ Object 



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# File 'lib/command_handlers/models/observable_model.rb', line 40

def property_observer_hash
  @property_observers = Hash.new unless @property_observers
  @property_observers
end

#property_observer_list(property_name) ⇒ Object 



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# File 'lib/command_handlers/models/observable_model.rb', line 45

def property_observer_list(property_name)
  property_observer_hash[property_name.to_sym] = Set.new unless property_observer_hash[property_name.to_sym]
  property_observer_hash[property_name.to_sym]
end

#remove_observer(observer, property_name) ⇒ Object 



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# File 'lib/command_handlers/models/observable_model.rb', line 28

def remove_observer(observer, property_name)
  property_observer_list(property_name).delete(observer)
end

#unregister_dependent_observers(property_name, old_value) ⇒ Object 



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# File 'lib/command_handlers/models/observable_model.rb', line 78

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