PHP static wierdness

print-1.php

<?php

# Example with function
function print_first_value(&$value)
{
    static $keep = NULL;
    if ($keep === NULL) {
        print "Setting $value.\n";
        $keep = &$value; # NOTE: using $value by reference
    }
    print preg_replace('#\s+#', ' ', var_export($keep, TRUE)) . "\n";
}

$value1 = 1; print_first_value($value1); # prints 1 as expected
$value2 = 2; print_first_value($value2); # prints 2!

print-2.php

<?php

# Example with a class wrapper
class Print_
{
    static $keep = NULL;
    static function first_value(&$value)
    {
        if (self::$keep === NULL) {
            print "Setting $value.\n";
            self::$keep = &$value; # NOTE: using $value by reference
        }
        print preg_replace('#\s+#', ' ', var_export(self::$keep, TRUE)) . "\n";
    }
}

$value1 = 1; Print_::first_value($value1); # prints 1 as expected
$value2 = 2; Print_::first_value($value2); # prints 1 as expected

print-3.php

<?php

# Example with function and static using an array()
function print_first_value(&$value)
{
    static $keep = array();
    if (sizeof ($keep) < 1) {
        print "Setting $value.\n";
        $keep[] = &$value;
    }
    print preg_replace('#\s+#', ' ', var_export($keep, TRUE)) . "\n";
}

$value1 = 1; print_first_value($value1); # prints 1 as expected
$value2 = 2; print_first_value($value2); # prints 1 as expected