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PHP Object-Oriented PHP Basics (Retired) Inheritance, Interfaces, and Exceptions Class and Method Interaction

geoffrey
geoffrey
28,724 Points

Class and Method Interaction

I'm finishing the introduction about POO in PHP but there is someting I don't get. When creation an object we do this:

$soda  = new Product();     /* we use parenthesis  in this case.*/

But in the video here, Paulk shows a little trick. He does this:

$class = "Product";
$p = new $class;     /* in other words $p = new Product*/

/*But why don't we need to specify the parenthesis, why not doing this ? */

$class =  "Product()";
$p = new $class;

/* I haven't tested yet, as where I'm atm, It's not possible.*/

Hi geoffrey,

We care about all countries, large or small.

Jeff

geoffrey
geoffrey
28,724 Points

lol It seems you've just read my profile. I wrote this because for the most part of the world, we don't even exist :)

2 Answers

Chris Shaw
Chris Shaw
26,650 Points

Hi geoffrey,

The parenthesis while they are good practise to use aren't required for classes that don't require any arguments for the constructor, so for example all 3 of the below constructors are exactly the same when the constructor runs.

<?php

$p = new Product();
$p = new Product;

$class = 'Product';
$p = new $class;

The last example you have above won't work as the parenthesis are invalid and can't be evaluated as a class name because there is no such class called Product() which is impossible anyway.

Hope that helps.

geoffrey
geoffrey
28,724 Points

Yes, that helped, thank you.