The following codes didn't work as expected. There're two problems that I don't understand.

First, PHP doesn't know about defined constant if test() is called from subclass.

<?php
define('TEN', 10);
class Foo {
    function test() {
        static $arr = array(TEN => 'ten');

        print_r($arr);
    }
}

class Bar extends Foo {
}

Foo::test();    // output: Array([10] => ten)
Bar::test();    // output: Array([TEN] => ten)
?>


Second, as commented, it doesn't know about const TEN too.

<?php
class Foo {
    const TEN = 10;
    function test() {
        // --- PHP will complain about this
        // static $arr = array(TEN => 'ten');

        // --- This line cause $arr to be an empty array
        //     without any error
        static $arr = array(Foo::TEN => 'ten');

        print_r($arr);
    }
}

Foo::test();    // output: Array()
?>