In PHP, how can I create a class from a variable?

Problem

Because this question appears to be a little hazy, I’ll use an example to clarify it:

$var = 'bar';
$bar = new {$var}Class('var for __construct()'); //$bar = new barClass('var for __construct()');

This is exactly what I intend to accomplish. How would you go about doing it? Of course, I could use eval() in the following way:

$var = 'bar';
eval('$bar = new '.$var.'Class(\'var for __construct()\');');

However, I’d rather avoid eval (). Is there a way to accomplish this without using eval()?

Asked by Pim Jager

Solution #1

First, create a variable for the classname:

$classname=$var.'Class';

$bar=new $classname("xyz");

This is something you’ll frequently find wrapped up in a Factory pattern.

For further information, see Namespaces and dynamic language features.

Answered by Paul Dixon

Solution #2

In my experience, I believe it’s important to point out that you must define the whole namespace path of a class (as far as I can tell).

MyClass.php

namespace com\company\lib;
class MyClass {
}

index.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;

Answered by csga5000

Solution #3

You can use this code to pass dynamic constructor parameters to the class:

$reflectionClass = new ReflectionClass($className);

$module = $reflectionClass->newInstanceArgs($arrayOfConstructorParameters);

More details on dynamic classes and parameters may be found here.

With PHP 5.6, you can further simplify this by using Argument Unpacking:

// The "..." is part of the language and indicates an argument array to unpack.
$module = new $className(...$arrayOfConstructorParameters);

DisgruntledGoat was the one who pointed it up.

Answered by flu

Solution #4

class Test {
    public function yo() {
        return 'yoes';
    }
}

$var = 'Test';

$obj = new $var();
echo $obj->yo(); //yoes

Answered by zalew

Solution #5

The call user func() and call user func arrayphp methods come highly recommended. They’re available here (call user func array, call user func).

example

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 want to send parameters to the method, use the call user func array() function.

example.

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"));

Answered by pickman murimi

Post is based on https://stackoverflow.com/questions/534159/instantiate-a-class-from-a-variable-in-php