how to instantiate an object with class name in a variable? [duplicate] - php

Question

I have two classes, class ClassOne { } and class ClassTwo {}. I am getting a string which can be either "One" or "Two".
Instead of using a long switch statement such as:
switch ($str) {
case "One":
return new ClassOne();
case "Two":
return new ClassTwo();
}
Is there a way I can create an instance using a string, i.e. new Class("Class" . $str);?

Answer 1

Yes, you can!
$str = 'One';
$class = 'Class'.$str;
$object = new $class();
When using namespaces, supply the fully qualified name:
$class = '\Foo\Bar\MyClass';
$instance = new $class();
Other cool stuff you can do in php are:
Variable variables:
$personCount = 123;
$varname = 'personCount';
echo $$varname; // echo's 123
And variable functions & methods.
$func = 'my_function';
$func('param1'); // calls my_function('param1');
$method = 'doStuff';
$object = new MyClass();
$object->$method(); // calls the MyClass->doStuff() method.

Answer 2

You can simply use the following syntax to create a new class (this is handy if you're creating a factory):
$className = $whatever;
$object = new $className;
As an (exceptionally crude) example factory method:
public function &factory($className) {
require_once($className . '.php');
if(class_exists($className)) return new $className;
die('Cannot create new "' . $className . '" class - includes not found or class unavailable.');
}

Answer 3

have a look at example 3 from http://www.php.net/manual/en/language.oop5.basic.php
$className = 'Foo';
$instance = new $className(); // Foo()

Answer 4

Lets say ClassOne is defined as:
public class ClassOne
{
protected $arg1;
protected $arg2;
//Contructor
public function __construct($arg1, $arg2)
{
$this->arg1 = $arg1;
$this->arg2 = $arg2;
}
public function echoArgOne
{
echo $this->arg1;
}
}
Using PHP Reflection;
$str = "One";
$className = "Class".$str;
$class = new \ReflectionClass($className);
Create a new Instance:
$instance = $class->newInstanceArgs(["Banana", "Apple")]);
Call a method:
$instance->echoArgOne();
//prints "Banana"
Use a variable as a method:
$method = "echoArgOne";
$instance->$method();
//prints "Banana"
Using Reflection instead of just using the raw string to create an object gives you better control over your object and easier testability (PHPUnit relies heavily on Reflection)

Answer 5

// Way #1
$className = "App\MyClass";
$instance = new $className();
// Way #2
$className = "App\MyClass";
$class = new \ReflectionClass($className);
// Create a new Instance without arguments:
$instance = $class->newInstance();
// Create a new Instance with arguments (need a contructor):
$instance = $class->newInstanceArgs(["Banana", "Apple"]);