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);?
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();
You can also call variable functions & methods dynamically.
$func = 'my_function';
$parameters = ['param2', 'param2'];
$func(...$parameters); // calls my_function() with 2 parameters;
$method = 'doStuff';
$object = new MyClass();
$object->$method(); // calls the MyClass->doStuff() method.
// or in one call
(new MyClass())->$method();
Also PHP can create variables with a string as well, but it's a really bad practice that should be avoided whenever possible. Consider to use arrays instead.
$my_obj = Package\$class_name();. Instead you have to $class_name = "Package\\" . $class_name; $my_obj = new $class_name();
$className = '\Foo\Bar\MyClass'; $instance = new $className();
$model = $user_model::find()->All(); where $user_model is the variable containing the string of the class being called
$className = '\\Foo\\Bar\\MyClass'; … right?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 "' . $className . '" class - includes not found or class unavailable.');
}
require_once($className.'php'); -> require_once($className.'.php');have a look at example 3 from http://www.php.net/manual/en/language.oop5.basic.php
$className = 'Foo';
$instance = new $className(); // Foo()
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)
// 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"]);
In case you have a namespace at the top of the file.
import the desired class at the top of the current file:
use \Foo\Bar\MyClass;
// Assign the class namespace to a variable.
$class = MyClass::class;
// Create a new instance
$instance = new $class();
The ::class will return the entire namespace of the desired class
