Module: Observer

Included in:
BlockObserver, ListSelectionBinding, ModelBinding, ObservableModel::Updater, TableItemsBinding, TreeItemsBinding, WidgetBinding
Defined in:
lib/command_handlers/models/observer.rb

Overview

Mixin representing Observer trait from Observer Design Pattern Allows classes to include without interfering with their inheritance hierarchy.

Instance Method Summary collapse

Instance Method Details

#add_dependent(parent_to_dependent_hash) ⇒ Object

add dependent observer to unregister when unregistering observer



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# File 'lib/command_handlers/models/observer.rb', line 73

def add_dependent(parent_to_dependent_hash)
  observable, property = registration = parent_to_dependent_hash.keys.first
  dependent_observer, dependent_observable, dependent_property = dependent = parent_to_dependent_hash.values.first
  dependents_for(registration) << dependent
end

#dependents ⇒ Object

mapping of registrations to dependents property] => [[dependent, dependent_observable, dependent_property], …]



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# File 'lib/command_handlers/models/observer.rb', line 17

def dependents
  @dependents ||= Hash.new
end

#dependents_for(registration) ⇒ Object 



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

def dependents_for(registration)
  dependents[registration] ||= Set.new
end

#register(observable, property = nil) ⇒ Object Also known as: observe

registers observer in an observable on a property (optional) observer maintains registration list to unregister later



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# File 'lib/command_handlers/models/observer.rb', line 27

def register(observable, property = nil)
  unless observable.is_a?(Observable)
    # TODO refactor code to be more smart/polymorphic/automated and honor open/closed principle
    if observable.is_a?(Array)
      observable.extend(ObservableArray)
    else
      observable.extend(ObservableModel)
    end
  end
  observable.add_observer(*[self, property].compact)
  [observable, property].tap do |registration|
    self.registrations << registration
  end
end

#registrations ⇒ Object 



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# File 'lib/command_handlers/models/observer.rb', line 7

def registrations
  @registrations ||= Set.new
end

#registrations_for(observable, property = nil) ⇒ Object 



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# File 'lib/command_handlers/models/observer.rb', line 11

def registrations_for(observable, property = nil)
  registrations.select {|o, p| o == observable && p == property}
end

#remove_dependent(parent_to_dependent_hash) ⇒ Object 



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# File 'lib/command_handlers/models/observer.rb', line 79

def remove_dependent(parent_to_dependent_hash)
  observable, property = registration = parent_to_dependent_hash.keys.first
  dependent_observer, dependent_observable, dependent_property = dependent = parent_to_dependent_hash.values.first
  dependents_for(registration).delete(dependent)
end

#unregister(observable, property = nil) ⇒ Object Also known as: unobserve 



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

def unregister(observable, property = nil)
  observable.remove_observer(*[self, property].compact)
  registration = [observable, property]
  dependents_for(registration).each do |dependent|
    dependent_observer, dependent_observable, dependent_property = dependent
    dependent_observer.unregister(dependent_observable, dependent_property)
    remove_dependent(registration => dependent)
  end
  registrations.delete(registration)
end

#unregister_all_observables ⇒ Object Also known as: unobserve_all_observables

cleans up all registrations in observables



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# File 'lib/command_handlers/models/observer.rb', line 65

def unregister_all_observables
  registrations.each do |observable, property|
    unregister(observable, property)
  end
end

#unregister_dependents_with_observable(registration, dependent_observable) ⇒ Object 



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

def unregister_dependents_with_observable(registration, dependent_observable)
  thedependents = dependents_for(registration).select do |d_observer, d_observable, d_property|
    d_observable == dependent_observable
  end
  thedependents.each do |d_observer, d_observable, d_property|
    d_observer.unregister(d_observable, d_property)
  end
end

#update(changed_value) ⇒ Object 



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# File 'lib/command_handlers/models/observer.rb', line 85

def update(changed_value)
  raise 'Not implemented!'
end