为什么类的私有数组中没有函数

Question

I've tried to access a function in a class private array, but i've got an error:

Parse error: syntax error, unexpected '(', expecting ')' in CODE on line 17 Errors parsing CODE

this is my code:

<?php

function foo_function () {

    return 'foo_value';
}

class foo {

    private $good_foo_var = array (

        'foo_key' => 'anything'
    );

    private $bad_foo_var = array (

        'foo_key' => foo_function ()
    );

    public function get_the_foo () {

        return $this -> foo_var['foo_key'];

    }

}

I have no idea why. Outside a class this kind of assignment is no problem.

Answer 1

Properties which are defined in your class are instantiated during compile-time. This means that the value is not evaluated, but has to be a constant value. Function returns are not constant values, so have to be evaluated during run-time. For this you should instantiate them in your constructor.

See for more information the PHP documentation