Question

I’m refreshing my PHP knowledge and have a problem I can’t solve on my own:

I have a class with two private static arrays that I want to store as values of a further (multideimensional) static class array but I always get a *unexpected T_VARIABLE* error. Here is my simplyfied sample code (just with one instead of two static arrays to fill in the following multidimensional array) that fails:

class MyClass {
  private static $firstArr = array('a' => 'A', 'b' => 'B');

  private static $multiArr = array('a' => self::$firstArr);
}

I really don’t understand what’s wrong here. I could easily replace the self::$firstArr with the array declaration of $firstArr itself, but I’d love to understand what I’m doing wrong here, anyway.

So any comment is welcome!

Cheers,
Roman.

Answer 1

You can’t do any kind of extra evaluation when declaring class properties.

private static $multiArr = array('a' => self::$firstArr);
//                Can't do this    -----^

Link in docs

This declaration may include an initialization, but this initialization must be a constant value–that is, it must be able to be evaluated at compile time and must not depend on run-time information in order to be evaluated.

You’re right to avoid copy/paste – This sort of ‘run-time information’ is usually done in the constructor.