<?php /** * @link http://www.yiiframework.com/ * @copyright Copyright (c) 2008 Yii Software LLC * @license http://www.yiiframework.com/license/ */ namespace yii\caching; /** * ExpressionDependency represents a dependency based on the result of a PHP expression. * * ExpressionDependency will use `eval()` to evaluate the PHP expression. * The dependency is reported as unchanged if and only if the result of the expression is * the same as the one evaluated when storing the data to cache. * * A PHP expression can be any PHP code that has a value. To learn more about what an expression is, * please refer to the [php manual](http://www.php.net/manual/en/language.expressions.php). * * @author Qiang Xue <qiang.xue@gmail.com> * @since 2.0 */ class ExpressionDependency extends Dependency { /** * @var string the string representation of a PHP expression whose result is used to determine the dependency. * A PHP expression can be any PHP code that evaluates to a value. To learn more about what an expression is, * please refer to the [php manual](http://www.php.net/manual/en/language.expressions.php). */ public $expression = 'true'; /** * @var mixed custom parameters associated with this dependency. You may get the value * of this property in [[expression]] using `$this->params`. */ public $params; /** * Generates the data needed to determine if dependency has been changed. * This method returns the result of the PHP expression. * @param Cache $cache the cache component that is currently evaluating this dependency * @return mixed the data needed to determine if dependency has been changed. */ protected function generateDependencyData($cache) { return eval("return {$this->expression};"); } }