diff --git a/docs/api/framework/base/Object.md b/docs/api/framework/base/Object.md
index d61486d..6764504 100644
--- a/docs/api/framework/base/Object.md
+++ b/docs/api/framework/base/Object.md
@@ -34,6 +34,3 @@ One can call [[hasProperty]], [[canGetProperty]] and/or [[canSetProperty]] to ch
 
 Besides the property feature, the Object class defines a static method [[create]] which provides a convenient
 alternative way of creating a new object instance.
-
-The Object class also defines the [[evaluateExpression]] method so that a PHP expression or callback can be dynamically
-evaluated within the context of an object.
\ No newline at end of file
diff --git a/framework/base/Component.php b/framework/base/Component.php
index 4767803..e8e814b 100644
--- a/framework/base/Component.php
+++ b/framework/base/Component.php
@@ -92,7 +92,7 @@ class Component extends \yii\base\Object
 		} elseif (strncmp($name, 'as ', 3) === 0) {
 			// as behavior: attach behavior
 			$name = trim(substr($name, 3));
-			$this->attachBehavior($name, \Yii::createObject($value));
+			$this->attachBehavior($name, $value instanceof Behavior ? $value : \Yii::createObject($value));
 		} else {
 			// behavior property
 			$this->ensureBehaviors();
diff --git a/framework/base/Object.php b/framework/base/Object.php
index 3cd5d12..770234a 100644
--- a/framework/base/Object.php
+++ b/framework/base/Object.php
@@ -180,41 +180,6 @@ class Object
 	}
 
 	/**
-	 * Evaluates a PHP expression or callback under the context of this object.
-	 *
-	 * Valid PHP callback can be class method name in the form of
-	 * array(ClassName/Object, MethodName), or anonymous function.
-	 *
-	 * If a PHP callback is used, the corresponding function/method signature should be
-	 *
-	 * ~~~
-	 * function foo($param1, $param2, ..., $object) { ... }
-	 * ~~~
-	 *
-	 * where the array elements in the second parameter to this method will be passed
-	 * to the callback as `$param1`, `$param2`, ...; and the last parameter will be the object itself.
-	 *
-	 * If a PHP expression is used, the second parameter will be "extracted" into PHP variables
-	 * that can be directly accessed in the expression.
-	 * See [PHP extract](http://us.php.net/manual/en/function.extract.php)
-	 * for more details. In the expression, the object can be accessed using `$this`.
-	 *
-	 * @param mixed $_expression_ a PHP expression or PHP callback to be evaluated.
-	 * @param array $_data_ additional parameters to be passed to the above expression/callback.
-	 * @return mixed the expression result
-	 */
-	public function evaluateExpression($_expression_, $_data_ = array())
-	{
-		if (is_string($_expression_)) {
-			extract($_data_);
-			return eval('return ' . $_expression_ . ';');
-		} else {
-			$_data_[] = $this;
-			return call_user_func_array($_expression_, $_data_);
-		}
-	}
-
-	/**
 	 * Creates a new instance of the calling class.
 	 *
 	 * The newly created object will be initialized with the specified configuration.
diff --git a/framework/caching/ExpressionDependency.php b/framework/caching/ExpressionDependency.php
index 19b3b48..a553cdc 100644
--- a/framework/caching/ExpressionDependency.php
+++ b/framework/caching/ExpressionDependency.php
@@ -12,9 +12,8 @@ namespace yii\caching;
 /**
  * ExpressionDependency represents a dependency based on the result of a PHP expression.
  *
- * ExpressionDependency performs dependency checking based on the
- * result of a PHP {@link expression}.
- * The dependency is reported as unchanged if and only if the result is
+ * 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.
  *
  * @author Qiang Xue <qiang.xue@gmail.com>
@@ -24,10 +23,6 @@ class ExpressionDependency extends Dependency
 {
 	/**
 	 * @var string the PHP expression whose result is used to determine the dependency.
-	 * The expression can also be a valid PHP callback,
-	 * including class method name (array(ClassName/Object, MethodName)),
-	 * or anonymous function (PHP 5.3.0+). The function/method will be passed with a
-	 * parameter which is the dependency object itself.
 	 */
 	public $expression;
 
@@ -47,6 +42,6 @@ class ExpressionDependency extends Dependency
 	 */
 	protected function generateDependencyData()
 	{
-		return $this->evaluateExpression($this->expression);
+		return eval("return {$this->expression};");
 	}
 }
diff --git a/tests/unit/framework/base/ObjectTest.php b/tests/unit/framework/base/ObjectTest.php
index feb2742..0557140 100644
--- a/tests/unit/framework/base/ObjectTest.php
+++ b/tests/unit/framework/base/ObjectTest.php
@@ -116,13 +116,6 @@ class ObjectTest extends \yiiunit\TestCase
 		$this->assertTrue(isset($this->object->Text));
 		$this->assertTrue(empty($this->object->Text));
 	}
-
-	public function testEvaluateExpression()
-	{
-		$object = new NewObject;
-		$this->assertEquals('Hello world',$object->evaluateExpression('"Hello $who"',array('who' => 'world')));
-		$this->assertEquals('Hello world',$object->evaluateExpression(array($object,'exprEvaluator'),array('who' => 'world')));
-	}
 }