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Date: Thu, 12 Aug 2004 11:30:28 +0800
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To: Dan Ostrowski <dan@ostrowski.cc>
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Subject: Re: [PHP-DEV] is_a() vs. instanceof
From: alan@akbkhome.com (Alan Knowles)

I think he's referening to something like this (which is common in pear):

$x = $someobj->somemethod();
if ($x instanceOf PEAR_Error) {
   .......
}

while that code is redundant in the case of exceptions, it is still a 
valid situation.. that $x may be a valid return, and PEAR_Error was 
never loaded..

Regards
Alan




Dan Ostrowski wrote:

>On Tuesday 10 August 2004 7:36 pm, Hans Lellelid wrote:
>  
>
>>I like the new $obj instanceof ClassName way of checking class /
>>interface types, .... but this method does have one major drawback
>>compared to the old is_a() approach:
>>
>>    The class must be loaded in order to perform an instanceof check!
>>
>>    
>>
>
>Isn't that the point? is_a() and instanceof are ways of checking the class of 
>an object at runtime where it could be any number of things. ( And here I'm 
>assuming you mean instantiated instead of "loaded"? )
>
>If you don't have an instantiated object.. what do you have? A class! And THAT 
>can be checked at "compile" ( or in this case write ) time. There's something 
>wrong with my code, if I'm thinking of this right, if I have no idea if class 
>A is a subclass of class B.
>
>Now, if I'm passed random objects, I may want to know of which types they 
>are... which is where these functions/builtins come in...
>
>Am I misunderstanding you?
>
>
>Dan Ostrowski
>
>  
>