从 PHP 中的变量实例化一个类？
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instantiate a class from a variable in PHP?
提问by Pim Jager
I know this question sounds rather vague so I will make it more clear with an example:
我知道这个问题听起来很模糊，所以我会用一个例子更清楚地说明：
$var = 'bar';
$bar = new {$var}Class('var for __construct()'); //$bar = new barClass('var for __construct()');
This is what I want to do. How would you do it? I could off course use eval() like this:
这就是我想要做的。你会怎么做？我当然可以像这样使用 eval() ：
$var = 'bar';
eval('$bar = new '.$var.'Class(\'var for __construct()\');');
But I'd rather stay away from eval(). Is there any way to do this without eval()?
但我宁愿远离 eval()。没有 eval() 有没有办法做到这一点？
回答by Paul Dixon
Put the classname into a variable first:
首先将类名放入变量中：
$classname=$var.'Class';
$bar=new $classname("xyz");
This is often the sort of thing you'll see wrapped up in a Factory pattern.
这通常是您在工厂模式中看到的那种东西。
See Namespaces and dynamic language featuresfor further details.
有关更多详细信息，请参阅命名空间和动态语言功能。
回答by csga5000
If You Use Namespaces
如果您使用命名空间
In my own findings, I think it's good to mention that you (as far as I can tell) must declare the full namespace path of a class.
在我自己的发现中，我认为最好提及您（据我所知）必须声明类的完整命名空间路径。
MyClass.php
我的类.php
namespace com\company\lib;
class MyClass {
}
index.php
索引.php
namespace com\company\lib;
//Works fine
$i = new MyClass();
$cname = 'MyClass';
//Errors
//$i = new $cname;
//Works fine
$cname = "com\company\lib\".$cname;
$i = new $cname;
回答by flu
How to pass dynamic constructor parameters too
如何传递动态构造函数参数
If you want to pass dynamic constructor parameters to the class, you can use this code:
如果要将动态构造函数参数传递给类，可以使用以下代码：
$reflectionClass = new ReflectionClass($className);
$module = $reflectionClass->newInstanceArgs($arrayOfConstructorParameters);
More information on dynamic classes and parameters
PHP >= 5.6
PHP >= 5.6
As of PHP 5.6 you can simplify this even more by using Argument Unpacking:
从 PHP 5.6 开始，您可以使用Argument Unpacking进一步简化：
// The "..." is part of the language and indicates an argument array to unpack.
$module = new $className(...$arrayOfConstructorParameters);
Thanks to DisgruntledGoat for pointing that out.
感谢 DisgruntledGoat 指出这一点。
回答by zalew
class Test {
public function yo() {
return 'yoes';
}
}
$var = 'Test';
$obj = new $var();
echo $obj->yo(); //yoes
回答by pickman murimi
I would recommend the call_user_func()or call_user_func_arrayphp methods.
You can check them out here (call_user_func_array, call_user_func).
我会推荐call_user_func()或call_user_func_arrayphp 方法。您可以在此处查看它们（call_user_func_array、call_user_func）。
example
例子
class Foo {
static public function test() {
print "Hello world!\n";
}
}
call_user_func('Foo::test');//FOO is the class, test is the method both separated by ::
//or
call_user_func(array('Foo', 'test'));//alternatively you can pass the class and method as an array
If you have arguments you are passing to the method , then use the call_user_func_array()function.
如果您有传递给方法的参数，则使用该call_user_func_array()函数。
example.
例子。
class foo {
function bar($arg, $arg2) {
echo __METHOD__, " got $arg and $arg2\n";
}
}
// Call the $foo->bar() method with 2 arguments
call_user_func_array(array("foo", "bar"), array("three", "four"));
//or
//FOO is the class, bar is the method both separated by ::
call_user_func_array("foo::bar"), array("three", "four"));
