instantiating a class without assigning to a variable

Question

I have a need to call a class which will perform actions but which I know I will not be calling the methods of. This is a PHP application. Does anyone ever just do the following:

require('class.Monkeys.php');
new Monkeys(); //note I didn't assign it to a variable

Answer 1

Yes, that's perfectly valid. However, it is arguably bad form, because the golden rule is that:

Constructors should not do actual work.

A constructor should set up an object so that it is valid and in a "ready state". The constructor should not start to perform work on its own. As such, this would be saner:

$monkeys = new Monkeys;
$monkeys->goWild();

Or, if you prefer and are running a sufficiently advanced PHP version:

(new Monkeys)->goWild();

Answer 2

Well let just say that we have a classname called Monkeys.

File class.Monkeys.php

class Monkeys {

   function __construct()
   {
       $this->doSomething()
   }

   public function doSomething(){
       echo "new Monkeys()->doSomething() was called";
   }

   public function anotherMethod(){
       echo "new Monkeys()->anotherMethod() was called";
   }
}

Now you can instantiate the class on runtime without saving it into a variable.

require('class.Monkeys.php');
// you can just instantiate it and the constructur will be called automatically 
(new Monkeys());

// or you can instantiate it and call other methods
(new Monkeys())->anotherMethod();

I'm not sure if the garbage collector will delete the instantiated classes or not, but i assume since those classes are not saved into a variable this would not be saved somewhere in the memory and that would be perfect.