Can I instantiate a PHP class inside another class?

Question

I was wondering if it is allowed to create an instance of a class inside another class.

Or, do I have to create it outside and then pass it in through the constructor? But then I would have created it without knowing if I would need it.

Example (a database class):

class some{  if(.....){ include SITE_ROOT . 'applicatie/' . 'db.class.php'; $db=new db 

Answer 1

You can't define a class in another class. You should include files with other classes outside of the class. In your case, that will give you two top-level classes db and some. Now in the constructor of some you can decide to create an instance of db. For example:

include SITE_ROOT . 'applicatie/' . 'db.class.php';  class some {      public function __construct() {         if (...) {             $this->db = new db;         }     }  } 

Answer 2

People saying that it is possible to 'create a class within a class' seem to mean that it is possible to create an object / instance within a class. I have not seen an example of an actual class definition within another class definition, which would look like:

class myClass{      class myNestedClass{      }  }  /* THIS IS NOT ALLOWED AND SO IT WON'T WORK */ 

Since the question was 'is it possible to create a class inside another class', I can now only assume that it is NOT possible.