Detailed explanation of the use of reflection in PHP

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Release: 2023-04-08 22:20:01
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Detailed explanation of the use of reflection in PHP

# Let’s talk about the application of reflection in actual development.

  • Automatically generate documents
  • Implement MVC architecture
  • Implement unit testing
  • Cooperate with DI container to resolve dependencies

Automatically generate documents

Documents can be automatically generated based on the reflection analysis of classes, interfaces, internal structures of functions and methods, parameters of methods and functions, and attributes and methods of classes.

/** * 学生类 * * 描述信息 */ class Student { const NORMAL = 1; const FORBIDDEN = 2; /** * 用户ID * @var 类型 */ public $id; /** * 获取id * @return int */ public function getId() { return $this->id; } public function setId($id = 1) { $this->id = $id; } } $ref = new ReflectionClass('Student'); $doc = $ref->getDocComment(); echo $ref->getName() . ':' . getComment($ref) , "\n"; echo "属性列表:\n"; printf("%-15s%-10s%-40s\n", 'Name', 'Access', 'Comment'); $attr = $ref->getProperties(); foreach ($attr as $row) { printf("%-15s%-10s%-40s\n", $row->getName(), getAccess($row), getComment($row)); } echo "常量列表:\n"; printf("%-15s%-10s\n", 'Name', 'Value'); $const = $ref->getConstants(); foreach ($const as $key => $val) { printf("%-15s%-10s\n", $key, $val); } echo "\n\n"; echo "方法列表\n"; printf("%-15s%-10s%-30s%-40s\n", 'Name', 'Access', 'Params', 'Comment'); $methods = $ref->getMethods(); foreach ($methods as $row) { printf("%-15s%-10s%-30s%-40s\n", $row->getName(), getAccess($row), getParams($row), getComment($row)); } // 获取权限 function getAccess($method) { if ($method->isPublic()) { return 'Public'; } if ($method->isProtected()) { return 'Protected'; } if ($method->isPrivate()) { return 'Private'; } } // 获取方法参数信息 function getParams($method) { $str = ''; $parameters = $method->getParameters(); foreach ($parameters as $row) { $str .= $row->getName() . ','; if ($row->isDefaultValueAvailable()) { $str .= "Default: {$row->getDefaultValue()}"; } } return $str ? $str : ''; } // 获取注释 function getComment($var) { $comment = $var->getDocComment(); // 简单的获取了第一行的信息,这里可以自行扩展 preg_match('/\* (.*) *?/', $comment, $res); return isset($res[1]) ? $res[1] : ''; }
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Runphp file.phpto see the corresponding document information.

Implementing the MVC architecture

Many frameworks now have theMVCarchitecture. Locate the names of the controller ($controller) and the method ($method) based on the routing information, and then Use reflection to implement automatic calling.

$class = new ReflectionClass(ucfirst($controller) . 'Controller'); $controller = $class->newInstance(); if ($class->hasMethod($method)) { $method = $class->getMethod($method); $method->invokeArgs($controller, $arguments); } else { throw new Exception("{$controller} controller method {$method} not exists!"); }
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Detailed explanation of the use of reflection in PHP

##Implementing unit testing

Generally, we will test functions and classes to determine whether they can return results as we expect. We can use reflection to implement a simple and general class test case.


class Calc { public function plus($a, $b) { return $a + $b; } public function minus($a, $b) { return $a - $b; } } function testEqual($method, $assert, $data) { $arr = explode('@', $method); $class = $arr[0]; $method = $arr[1]; $ref = new ReflectionClass($class); if ($ref->hasMethod($method)) { $method = $ref->getMethod($method); $res = $method->invokeArgs(new $class, $data); var_dump($res === $assert); } } testEqual('Calc@plus', 3, [1, 2]); testEqual('Calc@minus', -1, [1, 2]);
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This is the test method of the class, and you can also use reflection to implement the test method of the function.

Here is just a test case I simply wrote.
PHPUnitThe unit testing framework relies heavily on the features ofReflection, you can learn more about it.

Cooperate with DI containers to resolve dependencies

LaravelMany frameworks such asReflectionare used to solve dependency injection problems. For details, please seeLaravelSource code for analysis.Below our code simply implements a
DIcontainer demonstrationReflectionto solve the dependency injection problem.

class DI { protected static $data = []; public function __set($k, $v) { self::$data[$k] = $v; } public function __get($k) { return $this->bulid(self::$data[$k]); } // 获取实例 public function bulid($className) { // 如果是匿名函数,直接执行,并返回结果 if ($className instanceof Closure) { return $className($this); } // 已经是实例化对象的话,直接返回 if(is_object($className)) { return $className; } // 如果是类的话,使用反射加载 $ref = new ReflectionClass($className); // 监测类是否可实例化 if (!$ref->isInstantiable()) { throw new Exception('class' . $className . ' not find'); } // 获取构造函数 $construtor = $ref->getConstructor(); // 无构造函数,直接实例化返回 if (is_null($construtor)) { return new $className; } // 获取构造函数参数 $params = $construtor->getParameters(); // 解析构造函数 $dependencies = $this->getDependecies($params); // 创建新实例 return $ref->newInstanceArgs($dependencies); } // 分析参数,如果参数中出现依赖类,递归实例化 public function getDependecies($params) { $data = []; foreach($params as $param) { $tmp = $param->getClass(); if (is_null($tmp)) { $data[] = $this->setDefault($param); } else { $data[] = $this->bulid($tmp->name); } } return $data; } // 设置默认值 public function setDefault($param) { if ($param->isDefaultValueAvailable()) { return $param->getDefaultValue(); } throw new Exception('no default value!'); } } class Demo { public function __construct(Calc $calc) { echo $calc->plus(1, 2); } } $di = new DI(); $di->calc = 'Calc'; // 加载单元测试用例中 Calc 类 $di->demo = 'Demo'; $di->demo;
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Note that the order of

calcanddemoabove cannot be reversed, otherwise an error will be reported. The reason is thatDemodepends onCalc, first define dependencies.When
Demois instantiated, theCalcclass will be used, which meansDemodepends onCalc, but in$dataIf the above is not found, an error will be thrown, so first define .Reflection is a very cool feature, use it, but don't abuse it.

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