ActiveSupport::Deprecation::DeprecatedConstantProxy

This DeprecatedConstantProxy transforms constant to deprecated constant.

OLD_CONST = ActiveSupport::Deprecation::DeprecatedConstantProxy.new('OLD_CONST', 'NEW_CONST')
OLD_CONST = ActiveSupport::Deprecation::DeprecatedConstantProxy.new('OLD_CONST', 'NEW_CONST', deprecator_instance)

When someone use old constant this will trigger warn method on deprecator_instance.

Default deprecator is ActiveSupport::Deprecation.