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Date: Sat, 19 Dec 2009 11:29:09 -0800
Message-ID: <c25f8d340912191129x4255461qe319f2bfb5c61133@mail.gmail.com>
To: Johannes Mueller <johannes_m@gmx.net>
Cc: internals@lists.php.net
Content-Type: text/plain; charset=UTF-8
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Subject: Re: [PHP-DEV] is_a() versus instanceof
From: 0xcafefeed@gmail.com (mm w)

class rootObject {
...
        function isMemberOrInstanceOfClass($object) {
                $className =3D is_object($object) ? get_class($object) : $o=
bject;
                return ($this instanceof $className);
        }
};

On Sat, Dec 19, 2009 at 2:20 AM, Johannes Mueller <johannes_m@gmx.net> wrot=
e:
> Johannes "Schl=C3=BCter" wrote:
>>
>> On Sat, 2009-12-19 at 01:42 +0100, Johannes Mueller wrote:
>>>
>>> if($foo instanceof bar){
>>> ..
>>> }
>>> // runs without any notification
>>
>> instanceof is a language construct expecting a class identifier.
>> It doesn't complain about on-existing classes as it would need to
>> trigger the __autoloader which might be way too much.
>>
>>> and
>>>
>>> if(is_a($foo, bar)){
>>> ..
>>> }
>>> // runs with an undefined constant bar notification
>>
>> is_a() is a function expecting a string. And this warning is unrelated
>> to the fact that the class "bar" doesn't exist, but due to the way PHP
>> treats undefined constants.
>
> Thank you for your answers, that is what I've expected. Unfortunately thi=
s
> is sometimes annoying when using namespaces, where you have to take care =
of
> the namespaces too.
>
> I do understand the performance impact of a more complex solution and my
> fault was to mix two different operations. I expected instanceof and is_a=
()
> to check if the class exists.
>
> My personal problem was, that I didn't recognized instanceof to treat the
> requested class as a normal string, even it is not enclosed by quotation
> marks.
>
> The only protective barrier in this case seems to be a skilled IDE, that
> helps you to avoid referencing non existant classes.
>
> Cheers
> Johannes
>
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