What is the reason the following code works and generates the given result. Is it a special language construct that is just supported by PHP? If so, then which one? Or is it just a simple php-ism?
class Foo {};
$a = new Foo();
$b = new $a();
var_dump($a); // class Foo#1 (0)
var_dump($b); // class Foo#2 (0)
PHP allows you to create an object instance from a variable like this:
$a = 'Foo';
$b = new $a;
So when you use the new $a, PHP is checking if it's a string to make a new instance of the class, and if it's an object, it's going to retrieve the class name of the object instance and make a new instance from it.
If you try to do the same with a non-string or non-object variable:
$a = 1;
$b = new $a;
This will generate an error:
PHP Error: Class name must be a valid object or a string
PHP 5.3.0 introduced a couple of new ways to create instances of an object, which is an example of a scenario like you've provided:
class Test {}
$obj1 = new Test();
$obj2 = new $obj1;
For more information: Read Example #5 Creating new objects under https://www.php.net/manual/en/language.oop5.basic.php#language.oop5.basic.new
$b = new get_class($a); throws me a fatal error. I am sure there is some syntactical mistake. If I store the return in a variable, it runs fine.