It should be noted that the the values in the array are mapped to constructor arguments positionally, rather than by name, so using an associative array will not make any difference.
(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
$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。
args这个参数以 array 形式传递到类的构造函数。
返回类的新实例，失败时返回 null。
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 #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"
}
It should be noted that the the values in the array are mapped to constructor arguments positionally, rather than by name, so using an associative array will not make any difference.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 $property =>
// string(9) "It works!"
// }
?>I use reflection class and also detect whether arguments are passed by reference or passed by value
and then initiate/call the method successfully with those arguments:
<?php
if (count($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) $re_args);
}
?>This is the way I dynamically instantiate objects in my lightweight IoC container
<?php
class SimpleContainer {
// ...
// Creates an instance of an object with the provided array of arguments
protected function instantiate($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.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
*/
?>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"
?>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.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()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.