PHP Conference Nagoya 2025

    ReflectionClass::newInstanceArgs

    (PHP 5 >= 5.1.3, PHP 7, PHP 8)

    ReflectionClass::newInstanceArgs — 从给出的参数创建一个新的类实例

    说明

    public ReflectionClass::newInstanceArgs(array $args = []): ?object

    创建一个类的新实例，给出的参数将传递到类的构造函数。

    参数

    args

    这个参数以 array 形式传递到类的构造函数。

    返回值

    返回类的新实例，失败时返回 null。

    错误／异常

    如果类的构造函数不是 public 的将导致产生 ReflectionException。

    当 args 指定了一个或多个参数，而类不具有构造函数时,将导致 ReflectionException。

    示例

    示例 #1 ReflectionClass::newInstanceArgs() 的基本用法

    <?php
    $class     = new ReflectionClass('ReflectionFunction');
    $instance = $class->newInstanceArgs(array('substr'));
    var_dump($instance);
    ?>

    以上示例会输出：

    object(ReflectionFunction)#2 (1) {
  ["name"]=>
  string(6) "substr"
}

    参见

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    用户贡献的备注 8 notes

    up
    4
    kirillsaksin at no-spam dot yandex dot ru
    9 years ago
    Hack to properly instantiate class with private constructor:

    <?php

    class TestClass
    {
    private     $property;
    private function     __construct($argument)
    {
    $this->property = $argument;
    }
    }

    $ref = new ReflectionClass(TestClass::class);
    $instance = $ref->newInstanceWithoutConstructor();
    var_dump($instance);
    echo     PHP_EOL . '------------------------' . PHP_EOL . PHP_EOL;
    $constructor = $ref->getConstructor();
    $constructor->setAccessible(true);
    $constructor->invokeArgs($instance, ['It works!']);
    var_dump($instance);

    // Output:
    // class TestClass#3 (1) {
    // private $property =>
    // NULL
    // }
    //
    // ------------------------
    //
    // class TestClass#3 (1) {
    // private $property =>
    // string(9) "It works!"
    // }

    ?>
    up
    5
    sarfraznawaz2005 at gmail dot com
    14 years ago
    I use reflection class and also detect whether arguments are passed by reference or passed by value
    and then initiate/call the method successfully with those arguments:

    <?php
    if (count($args) > 1)
    {
    if (    method_exists($class_name, '__construct') === false)
    {
    exit(    "Constructor for the class <strong>$class_name</strong> does not exist, you should not pass arguments to the constructor of this class!");
    }

    $refMethod = new ReflectionMethod($class_name, '__construct');
    $params = $refMethod->getParameters();

    $re_args = array();

    foreach(    $params as $key => $param)
    {
    if (    $param->isPassedByReference())
    {
    $re_args[$key] = &$args[$key];
    }
    else
    {
    $re_args[$key] = $args[$key];
    }
    }

    $refClass = new ReflectionClass($class_name);
    $class_instance = $refClass->newInstanceArgs((array) $re_args);
    }
    ?>
    up
    3
    richardcook at gmail dot com
    15 years ago
    the newInstanceArgs function cannot call a class' constructor if it has references in its arguments, so be careful what you pass into it:

    <?php
    class Foo {
    function     __construct (&$arr) {
    $this->arr = &$arr;
    }
    function     createInstance () {
    $reflectionClass = new ReflectionClass("Bar");

    return     $reflectionClass->newInstanceArgs(array($this, $this->arr));
    }
    function     mod($key, $val) {
    $this->arr[$key] = $val;
    }
    }

    class     Bar {
    function     __construct (&$foo, &$arr) {
    $this->foo = &$foo;
    $this->arr = &$arr;
    }
    function     mod($key, $val) {
    $this->arr[$key] = $val;
    }
    }

    $arr = array();

    $foo = new Foo($arr);

    $arr["x"] = 1;

    $foo->mod("y", 2);

    $bar = $foo->createInstance();

    $bar->mod("z", 3);

    echo     "<pre>";
    print_r($arr);
    print_r($foo);
    print_r($bar);
    echo     "</pre>";

    /*
    Output:
    Warning: Invocation of Bar's constructor failed in [code path] on line 31

    Fatal error: Call to a member function mod() on a non-object in [code path] on line 58
    */
    ?>
    up
    2
    talk at stephensugden dot com
    14 years ago
    This is the way I dynamically instantiate objects in my lightweight IoC container

    <?php

    class SimpleContainer {

    // ...

    // Creates an instance of an object with the provided array of arguments
    protected function instantiate($name, $args=array()){
    if(empty(    $args))
    return new     $name();
    else {
    $ref = new ReflectionClass($name);
    return     $ref->newInstanceArgs($args);
    }
    }
    // ...
    }
    ?>

    I explicitly do NOT handle the case where a user passes constructor arguments for a constructor-less class, as I this SHOULD fail.
    up
    2
    dev at yopmail dot com
    9 years ago
    With PHP 5.6, we can use the ... (T_ELLIPSIS) operator

    <?php

    class Test {
    public function     __construct($a, $b) {
    echo     $a . ' ' . $b;
    }
    }

    $args = array(12, 34);
    new     Test(... $args); // Displays "12 34"

    ?>
    up
    -2
    sausage at tehsausage dot com
    14 years ago
    Annoyingly, this will throw an exception for classes with no constructor even if you pass an empty array for the arguments. For generic programming you should avoid this function and use call_user_func_array with newInstance.
    up
    -1
    kevinpeno at gmail dot com
    15 years ago
    I misunderstood this function to be a sort of setter of Reflection::newInstance() arguments in an array form rather than a creator of new instances itself.

    This function is equivilant to call_user_func_array() while Reflection::newInstance() is equivilant to call_user_func()
    up
    -2
    gromit at mailinator dot com
    16 years ago
    Be aware that calling the method newInstanceArgs with an empty array will still call the constructor with no arguments. If the class has no constructor then it will generate an exception.

    You need to check if a constructor exists before calling this method or use try and catch to act on the exception.
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