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require 'set'
module ActiveModel
# Stores the enabled/disabled state of individual observers for
# a particular model class.
class ObserverArray < Array
attr_reader :model_class
def initialize(model_class, *args)
@model_class = model_class
super(*args)
end
# Returns true if the given observer is disabled for the model class.
def disabled_for?(observer)
disabled_observers.include?(observer.class)
end
# Disables one or more observers. This supports multiple forms:
#
# ORM.observers.disable :user_observer
# # => disables the UserObserver
#
# User.observers.disable AuditTrail
# # => disables the AuditTrail observer for User notifications.
# # Other models will still notify the AuditTrail observer.
#
# ORM.observers.disable :observer_1, :observer_2
# # => disables Observer1 and Observer2 for all models.
#
# ORM.observers.disable :all
# # => disables all observers for all models.
#
# User.observers.disable :all do
# # all user observers are disabled for
# # just the duration of the block
# end
def disable(*observers, &block)
set_enablement(false, observers, &block)
end
# Enables one or more observers. This supports multiple forms:
#
# ORM.observers.enable :user_observer
# # => enables the UserObserver
#
# User.observers.enable AuditTrail
# # => enables the AuditTrail observer for User notifications.
# # Other models will not be affected (i.e. they will not
# # trigger notifications to AuditTrail if previously disabled)
#
# ORM.observers.enable :observer_1, :observer_2
# # => enables Observer1 and Observer2 for all models.
#
# ORM.observers.enable :all
# # => enables all observers for all models.
#
# User.observers.enable :all do
# # all user observers are enabled for
# # just the duration of the block
# end
#
# Note: all observers are enabled by default. This method is only
# useful when you have previously disabled one or more observers.
def enable(*observers, &block)
set_enablement(true, observers, &block)
end
protected
def disabled_observers
@disabled_observers ||= Set.new
end
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 start_transaction
disabled_observer_stack.push(disabled_observers.dup)
each_subclass_array do |array|
array.start_transaction
end
end
def disabled_observer_stack
@disabled_observer_stack ||= []
end
def end_transaction
@disabled_observers = disabled_observer_stack.pop
each_subclass_array do |array|
array.end_transaction
end
end
def transaction
start_transaction
begin
yield
ensure
end_transaction
end
end
def each_subclass_array
model_class.descendants.each do |subclass|
yield subclass.observers
end
end
def set_enablement(enabled, observers)
if block_given?
transaction do
set_enablement(enabled, observers)
yield
end
else
observers = ActiveModel::Observer.descendants 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
each_subclass_array do |array|
array.set_enablement(enabled, observers)
end
end
end
end
end
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