API Updated aspect proxy service

- Updated AspectProxyService to handle multiple handlers for each proxied
  object's methods.
- Changed BeforeCallAspect to allow for providing a return value that
  should be returned to the caller instead of the proxied return value
- Changed AfterCallAspect behaviour to allow for returning the value of
  the aspect to the caller instead of the proxied return value

control/injector/AfterCallAspect.php

@@ -22,6 +22,8 @@ interface AfterCallAspect {
 	 *				The name of the method being called
 	 * @param string $args
 	 *				The arguments that were passed to the method call
+	 * @param mixed $result
+	 *				The result of calling the method on the real object
 	 */
-	public function afterCall($proxied, $method, $args);
+	public function afterCall($proxied, $method, $args, $result);
 }

control/injector/AopProxyService.php

@@ -14,13 +14,34 @@ class AopProxyService {
 
 	public $proxied;
 	
+	/**
+	 * Because we don't know exactly how the proxied class is usually called,
+	 * provide a default constructor
+	 */
+	public function __construct() {
+		
+	}
+
 	public function __call($method, $args) {
 		if (method_exists($this->proxied, $method)) {
 			$continue = true;
+			$result = null;
+			
 			if (isset($this->beforeCall[$method])) {
-				$result = $this->beforeCall[$method]->beforeCall($this->proxied, $method, $args);
-				if ($result === false) {
-					$continue = false;
+				$methods = $this->beforeCall[$method];
+				if (!is_array($methods)) {
+					$methods = array($methods);
+				}
+				foreach ($methods as $handler) {
+					$alternateReturn = null;
+					$proceed = $handler->beforeCall($this->proxied, $method, $args, $alternateReturn);
+					if ($proceed === false) {
+						$continue = false;
+						// if something is set in, use it
+						if ($alternateReturn) {
+							$result = $alternateReturn;
+						}
+					}
 				}
 			}
 
@@ -28,11 +49,20 @@ class AopProxyService {
 				$result = call_user_func_array(array($this->proxied, $method), $args);
 			
 				if (isset($this->afterCall[$method])) {
-					$this->afterCall[$method]->afterCall($this->proxied, $method, $args, $result);
+					$methods = $this->afterCall[$method];
+					if (!is_array($methods)) {
+						$methods = array($methods);
+					}
+					foreach ($methods as $handler) {
+						$return = $handler->afterCall($this->proxied, $method, $args, $result);
+						if (!is_null($return)) {
+							$result = $return;
+						}
+					}
 				}
-
-				return $result;
 			}
+
+			return $result;
 		}
 	}
 }

control/injector/BeforeCallAspect.php

@@ -20,6 +20,9 @@ interface BeforeCallAspect {
 	 *				The name of the method being called
 	 * @param string $args
 	 *				The arguments that were passed to the method call
+	 * @param mixed $alternateReturn
+	 *				An alternative return value that should be passed 
+	 *				to the caller. Only has effect of beforeCall returns false
 	 */
-	public function beforeCall($proxied, $method, $args);
+	public function beforeCall($proxied, $method, $args, &$alternateReturn);
 }

tests/injector/AopProxyTest.php

@@ -0,0 +1,107 @@
+<?php
+
+/**
+ * 
+ *
+ * @author <marcus@silverstripe.com.au>
+ * @license BSD License http://www.silverstripe.org/bsd-license
+ */
+class AopProxyTest extends SapphireTest {
+	public function testBeforeMethodsCalled() {
+		$proxy = new AopProxyService();
+		$aspect = new BeforeAfterCallTestAspect();
+		$proxy->beforeCall = array(
+			'myMethod'	=> $aspect
+		);
+
+		$proxy->proxied = new ProxyTestObject();
+		
+		$result = $proxy->myMethod();
+		
+		$this->assertEquals('myMethod', $aspect->called);
+		$this->assertEquals(42, $result);
+	}
+	
+	public function testBeforeMethodBlocks() {
+		$proxy = new AopProxyService();
+		$aspect = new BeforeAfterCallTestAspect();
+		$aspect->block = true;
+		
+		$proxy->beforeCall = array(
+			'myMethod'	=> $aspect
+		);
+
+		$proxy->proxied = new ProxyTestObject();
+		
+		$result = $proxy->myMethod();
+		
+		$this->assertEquals('myMethod', $aspect->called);
+		
+		// the actual underlying method will NOT have been called
+		$this->assertNull($result);
+		
+		// set up an alternative return value
+		$aspect->alternateReturn = 84;
+		
+		$result = $proxy->myMethod();
+		
+		$this->assertEquals('myMethod', $aspect->called);
+		
+		// the actual underlying method will NOT have been called,
+		// instead the alternative return value
+		$this->assertEquals(84, $result);
+	}
+	
+	public function testAfterCall() {
+		$proxy = new AopProxyService();
+		$aspect = new BeforeAfterCallTestAspect();
+		
+		$proxy->afterCall = array(
+			'myMethod'	=> $aspect
+		);
+
+		$proxy->proxied = new ProxyTestObject();
+		
+		$aspect->modifier = function ($value) {
+			return $value * 2;
+		};
+		
+		$result = $proxy->myMethod();
+		$this->assertEquals(84, $result);
+	}
+	
+}
+
+class ProxyTestObject {
+	public function myMethod() {
+		return 42;
+	}
+}
+
+class BeforeAfterCallTestAspect implements BeforeCallAspect, AfterCallAspect {
+	public $block = false;
+	
+	public $called;
+	
+	public $alternateReturn;
+	
+	public $modifier; 
+
+	public function beforeCall($proxied, $method, $args, &$alternateReturn) {
+		$this->called = $method;
+		
+		if ($this->block) {
+			if ($this->alternateReturn) {
+				$alternateReturn = $this->alternateReturn;
+			}
+			return false;
+		}
+	}
+
+	public function afterCall($proxied, $method, $args, $result) {
+		if ($this->modifier) {
+			$modifier = $this->modifier;
+			return $modifier($result);
+		}
+	}
+}