[PHP] Re: [PHP5]__get, __set and isset()

[Daniel Schierbeck]

M. Sokolewicz wrote:
next time, please read the isset documentation carefully. I quote:
[quote]isset() will return FALSE if testing a variable that has been set 
to NULL.[/quote]

Catalin Trifu wrote:
        Hi,
    Is this really a bug. I think not.
    There is no variable $o->a or $a->b in the class OO
there is only the variable $elem and $a and $b is a member
of that array
    So ...
    The fact that PHP5 provides __set and __get magic
functions does not mean that the actual variables exist with
that particular name in the class ?
    Perhaps it would be nice to have a __isset magic function ?
Cheers
Catalin

<?php
class OO
{
private $elem = array("a" => 1);
public function __get ($prop)
{
if (isset($this->elem[$prop])) {
return $this->elem[$prop];
} else {
return NULL;
}
}
public function __set ($prop, $val)
{
$this->elem[$prop] = $val;
}
}
$o = new OO();
echo isset($o->a) ? "yes\n" : "no\n";
echo isset($o->b) ? "yes\n" : "no\n";
echo is_null($o->a) ? "yes\n" : "no\n";
echo is_null($o->b) ? "yes\n" : "no\n";
?>
I expected something like this:
yes
no
no
yes
But got this:
no
no
no
yes
It looks like isset() can't handle object properties correctly. I'll 
post the bug on php.net.

--
Daniel Schierbeck 
Next time, please read my post carefully. $a is not NULL, it is 1. 
Therefore, isset($a) should return TRUE, which it does normally, just 
not when $a is returned via __get().

@catalin: Yes, a __isset() method would be ideal, but i still can't see 
why isset() shouldn't support the overloaded variables - after all, if 
you are able to access such a variable using the __get() method, why 
shouldn't you be able to check whether or not it has been set? 
Currently, if you want to check whether a variable in the $elem array is 
set, you would have to use this:

        $a = $o->a;
        echo isset($a) ? "yes\n" : "no\n";
Which in my opinion isn't optimal.
Bottom line - if you can access a variable through property overloading 
you should be able to use isset() on them as well.

--
Daniel Schierbeck
--
PHP General Mailing List (http://www.php.net/)
To unsubscribe, visit: http://www.php.net/unsub.php