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require 'set'
module ActiveModel
# Stores the enabled/disabled state of individual observers for
# a particular model classes.
class ObserverArray < Array
INSTANCES = Hash.new do |hash, model_class|
hash[model_class] = new(model_class)
end
def self.for(model_class)
return nil unless model_class < ActiveModel::Observing
INSTANCES[model_class]
end
# returns false if:
# - the ObserverArray for the given model's class has the given observer
# in its disabled_observers set.
# - or that is the case at any level of the model's superclass chain.
def self.observer_enabled?(observer, model)
klass = model.class
observer_class = observer.class
loop do
break unless array = self.for(klass)
return false if array.disabled_observers.include?(observer_class)
klass = klass.superclass
end
true # observers are enabled by default
end
def disabled_observers
@disabled_observers ||= Set.new
end
attr_reader :model_class
def initialize(model_class, *args)
@model_class = model_class
super(*args)
end
def disable(*observers, &block)
set_enablement(false, observers, &block)
end
def enable(*observers, &block)
set_enablement(true, observers, &block)
end
private
def observer_class_for(observer)
return observer if observer.is_a?(Class)
if observer.respond_to?(:to_sym) # string/symbol
observer.to_s.camelize.constantize
else
raise ArgumentError, "#{observer} was not a class or a " +
"lowercase, underscored class name as expected."
end
end
def transaction
orig_disabled_observers = disabled_observers.dup
begin
yield
ensure
@disabled_observers = orig_disabled_observers
end
end
def set_enablement(enabled, observers)
if block_given?
transaction do
set_enablement(enabled, observers)
yield
end
else
observers = ActiveModel::Observer.all_observers if observers == [:all]
observers.each do |obs|
klass = observer_class_for(obs)
unless klass < ActiveModel::Observer
raise ArgumentError.new("#{obs} does not refer to a valid observer")
end
if enabled
disabled_observers.delete(klass)
else
disabled_observers << klass
end
end
end
end
end
end
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