Module: Glimmer::DataBinding::Observer

Included in:
ModelBinding, Glimmer::DataBinding::ObservableArray::Notifier, Glimmer::DataBinding::ObservableHash::Notifier, Glimmer::DataBinding::ObservableModel::Notifier, Proc
Defined in:
lib/glimmer/data_binding/observer.rb

Overview

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

Includes a default implementation that can receive an observer block Example: Observer.proc {|new_value| puts new_value} Subclasses may override

Defined Under Namespace

Classes: Proc, Registration

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.proc(&observer_block) ⇒ Object 



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# File 'lib/glimmer/data_binding/observer.rb', line 58

def proc(&observer_block)
  Proc.new(&observer_block)
end

Instance Method Details

#add_dependent(parent_to_dependent_hash) ⇒ Object

add dependent observer to unregister when unregistering observer



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# File 'lib/glimmer/data_binding/observer.rb', line 139

def add_dependent(parent_to_dependent_hash)
  registration = parent_to_dependent_hash.keys.first
  dependent = parent_to_dependent_hash.values.first
  dependents_for(registration) << dependent
end

#call(new_value = nil, *extra_args) ⇒ Object

Raises:



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# File 'lib/glimmer/data_binding/observer.rb', line 153

def call(new_value = nil, *extra_args)
  raise Error, 'Not implemented!'
end

#compact_args(args) ⇒ Object 



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# File 'lib/glimmer/data_binding/observer.rb', line 157

def compact_args(args)
  args = args[0...-1] if args.last == {}
  args = args[0...-1] if args.last == []
  args.compact
end

#dependents ⇒ Object

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



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# File 'lib/glimmer/data_binding/observer.rb', line 75

def dependents
  @dependents ||= Concurrent::Hash.new
end

#dependents_for(registration) ⇒ Object 



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# File 'lib/glimmer/data_binding/observer.rb', line 79

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

#register(observable, *args) ⇒ Object Also known as: observe

registers observer in an observable on args usually containing a property and options (optional) observer maintains registration list to unregister later



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# File 'lib/glimmer/data_binding/observer.rb', line 85

def register(observable, *args)
  return if observable.nil?
  unless observable.is_a?(Observable)
    # TODO refactor code to be more smart/polymorphic/automated and honor open/closed principle (e.g. for SomeClass, search if there is ObservableSomeClass)
    if observable.is_a?(Array)
      observable.extend(ObservableArray)
    elsif observable.is_a?(Hash)
      observable.extend(ObservableHash)
    else
      observable.extend(ObservableModel)
    end
  end
  args = compact_args(args)
  observable.add_observer(self, *args)
  ensure_registration_for!(observable, *args)
end

#registration_for(observable, *args) ⇒ Object Also known as: ensure_registration_for! 



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# File 'lib/glimmer/data_binding/observer.rb', line 67

def registration_for(observable, *args)
  args = compact_args(args)
  registrations[[observable.object_id, args]] ||= Registration.new(observer: self, observable: observable, args: args)
end

#registrations ⇒ Object 



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# File 'lib/glimmer/data_binding/observer.rb', line 63

def registrations
  @registrations ||= Concurrent::Hash.new
end

#remove_dependent(parent_to_dependent_hash) ⇒ Object 



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# File 'lib/glimmer/data_binding/observer.rb', line 145

def remove_dependent(parent_to_dependent_hash)
  registration = parent_to_dependent_hash.keys.first
  dependent = parent_to_dependent_hash.values.first
  dependents_for(registration).delete(dependent).tap do
    dependents.delete([registration.object_id]) if dependents_for(registration).empty?
  end
end

#unregister(observable, *args) ⇒ Object Also known as: unobserve, deregister 



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# File 'lib/glimmer/data_binding/observer.rb', line 103

def unregister(observable, *args)
  return unless observable.is_a?(Observable)
  args = compact_args(args)
  registration = registration_for(observable, *args)
  registrations.delete([observable.object_id, args])
  registration.tap do |registration|
    dependents_for(registration).each do |dependent|
      remove_dependent(registration => dependent)
      dependent.deregister if dependent != registration
    end
    observable.remove_observer(self, *args)
  end
end

#unregister_all_observables ⇒ Object Also known as: unobserve_all_observables, deregister_all_observables

cleans up all registrations in observables



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# File 'lib/glimmer/data_binding/observer.rb', line 129

def unregister_all_observables
  registrations.values.dup.each do |registration|
    registration.deregister
    registrations.delete([registration.observable.object_id, registration.args])
  end
end

#unregister_dependents_with_observable(registration, dependent_observable) ⇒ Object Also known as: unobserve_dependents_with_observable, deregister_dependents_with_observable 



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# File 'lib/glimmer/data_binding/observer.rb', line 119

def unregister_dependents_with_observable(registration, dependent_observable)
  thedependents = dependents_for(registration).select do |thedependent|
    thedependent.observable == dependent_observable
  end
  thedependents.each(&:deregister)
end