* @since 2.0 */ class ExpressionDependency extends Dependency { /** * @var string the PHP expression whose result is used to determine the dependency. */ public $expression = 'true'; /** * Generates the data needed to determine if dependency has been changed. * This method returns the result of the PHP expression. * @return mixed the data needed to determine if dependency has been changed. */ protected function generateDependencyData() { return eval("return {$this->expression};"); } }