When should variables be set in a class

Question

Hay, when should variables be set within a PHP class?

<?php
    class MyClass {
        var $my_var;    // here? like var $my_var = null;
        function __construct(){
            $this->my_var = null; // or here?
        }
    }
?>

Answer 1

It depends what you want to initialise them to. I prefer to initialise them when they're declared if possible, but if they need to be, for example, the result of a method call, then you'll need to initialise them in the constructor.

Answer 2

i'd say

 class Foo 
 {
  public $bar = 'default';

  function __construct($custom_bar = null) {
   if(!is_null($custom_bar))
    $this->bar = $custom_bar;
  }

Answer 3

I'm thinking it would be best to initialize them in the constructor. I would normally think it's a matter of developer preference, but with the introduction of auto-implemented properties with C# 3.0, I think it makes more sense to simply put all intialization in the constructor(s) because you cannot supply a value to a property declared in this manner. And being consistent about where you intialize variables makes your code more readable.

Answer 4

Depends on the usage of the variable. OOP has always tried to emphasize that you initialize your variables in the contructor of the class.

Answer 5

As soon as you have enough info to set them correctly.

Answer 6

To me, a variable initialized at its declaration (outside of the constructor) looks too much like a constant. It's totally preference, but I choose to initialize in the constructor if at all possible.