PHP：如何使用另一个类中的参数实例化一个类
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PHP: How to instantiate a class with arguments from within another class
提问by Sarfraz
I am in a situations where i need to instantiate a class with arguments from within an instance of another class. Here is the prototype:
我处于需要使用另一个类的实例中的参数实例化一个类的情况。这是原型：
//test.php
class test
{
function __construct($a, $b, $c)
{
echo $a . '<br />';
echo $b . '<br />';
echo $c . '<br />';
}
}
Now, i need to instantiate above class using below class's clsfunction:
现在，我需要使用下面类的cls函数实例化上面的类：
class myclass
{
function cls($file_name, $args = array())
{
include $file_name . ".php";
if (isset($args))
{
// this is where the problem might be, i need to pass as many arguments as test class has.
$class_instance = new $file_name($args);
}
else
{
$class_instance = new $file_name();
}
return $class_instance;
}
}
Now when i try to create an instance of test class while passing arguments to it:
现在，当我尝试在向其传递参数的同时创建测试类的实例时：
$myclass = new myclass;
$test = $myclass->cls('test', array('a1', 'b2', 'c3'));
It gives error: Missing argument 1 and 2; only first argument is passed.
它给出了错误：缺少参数 1 和 2；只传递第一个参数。
This works fine if i instantiate a class which has no arguments in it's constructor function.
如果我实例化一个在其构造函数中没有参数的类，这很好用。
For experienced PHP developers, above should not be much of a problem. Please help.
对于有经验的 PHP 开发人员来说，上面应该不是什么大问题。请帮忙。
Thanks
谢谢
回答by user187291
you need Reflection http://php.net/manual/en/class.reflectionclass.php
你需要反射http://php.net/manual/en/class.reflectionclass.php
if(count($args) == 0)
$obj = new $className;
else {
$r = new ReflectionClass($className);
$obj = $r->newInstanceArgs($args);
}
回答by mauris
You can:
你可以：
1) Modify test class to accept an array, which contains the data you wish to pass.
1) 修改测试类以接受一个数组，其中包含您希望传递的数据。
//test.php
class test
{
function __construct($a)
{
echo $a[0] . '<br />';
echo $a[1] . '<br />';
echo $a[2] . '<br />';
}
}
2) initiate using a user method instead of the constructor and call it using the call_user_func_array()function.
2) 使用用户方法而不是构造函数启动并使用call_user_func_array()函数调用它。
//test.php
class test
{
function __construct()
{
}
public function init($a, $b, $c){
echo $a . '<br />';
echo $b . '<br />';
echo $c . '<br />';
}
}
In your main class:
在您的主要课程中：
class myclass
{
function cls($file_name, $args = array())
{
include $file_name . ".php";
if (isset($args))
{
// this is where the problem might be, i need to pass as many arguments as test class has.
$class_instance = new $file_name($args);
call_user_func_array(array($class_instance,'init'), $args);
}
else
{
$class_instance = new $file_name();
}
return $class_instance;
}
}
http://www.php.net/manual/en/function.call-user-func-array.php
http://www.php.net/manual/en/function.call-user-func-array.php
Lastly, you can leave your constructor params blank and use func_get_args().
最后，您可以将构造函数参数留空并使用func_get_args().
//test.php
class test
{
function __construct()
{
$a = func_get_args();
echo $a[0] . '<br />';
echo $a[1] . '<br />';
echo $a[2] . '<br />';
}
}
回答by alex
You could use call_user_func_array()I believe.
我相信你可以使用call_user_func_array()。
or you could leave the arguments list of the constructor, and then inside the constructor use this
或者你可以留下构造函数的参数列表，然后在构造函数中使用这个
$args = func_get_args();
回答by Cristian
class textProperty
{
public $start;
public $end;
function textProperty($start, $end)
{
$this->start = $start;
$this->end = $end;
}
}
$object = new textProperty($start, $end);
$object = new textProperty($start, $end);
don't work?
不工作？
回答by Thomas Decaux
The easiest way I have found:
我发现的最简单的方法：
if ($depCount === 0) {
$instance = new $clazz();
} elseif ($depCount === 1) {
$instance = new $clazz($depInstances[0]);
} elseif ($depCount === 2) {
$instance = new $clazz($depInstances[0], $depInstances[1]);
} elseif ($depCount === 3) {
$instance = new $clazz($depInstances[0], $depInstances[1], $depInstances[2]);
}
Sorry a bit raw, but you should understand the idea.
抱歉有点生硬，但你应该理解这个想法。
回答by Alexis Peters
We're in 2019 now and we have php7 now... and we have the spread-operator (...) . We can now simply call
我们现在在 2019 年，我们现在有 php7 ......我们有 spread-operator (...) 。我们现在可以简单地调用
<?php
class myclass
{
function cls($file_name, $args = array())
{
include $file_name . ".php";
if (isset($args))
{
$class_instance = new $file_name(...$args); // <-- notice the spread operator
}
else
{
$class_instance = new $file_name();
}
return $class_instance;
}
}
