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Posted by Jerry Stuckle on 08/09/06 11:50
wildernesscat wrote:
> Hi Jerry,
>
>
>>You can use is_a() as Marcin suggested. But what's to stop me from
>>creating my own class 'A'?
>
>
> As I told Marcin, is_a() will not be of much use here. I need an
> in-depth comparison, and not just resemblance in names.
>
>
>>The real question is - why do you need this "feature"? It violates
>>several principles of OO.
>
>
> Actually, I don't think that I violate any major OO principles. This is
> almost like asking an object whether it supports certain interfaces.
> I'll pinpoint my question. I want to know whether a certain object has
> the _public_ properties of a given class. Does that make sense? Suppose
> I have an object that has public properties $aaa, $bbb, and $ccc - I'd
> like to know whether class A also has them.
>
>
>>OO principles include that you don't care WHAT the object is - all you
>>care about is its interface (functions). If you need to depend on a
>>specific class, you need to rethink your design.
>>
>
>
> Regards,
> Danny
>
Danny,
Again, that's a completely different question.
No, there's nothing wrong to determine of a class supports specific
properties. But that's not the same as expecting a specific class.
And in many cases classes shouldn't have public properties - they should
have private properties and public access methods. It isolates the
interface from the implementation.
I see a lot of public properties in PHP code - mainly because before
PHP5 you couldn't define private properties. However, if you look at
C++, Java and Smalltalk, you'll find almost no public properties - only
methods.
--
==================
Remove the "x" from my email address
Jerry Stuckle
JDS Computer Training Corp.
jstucklex@attglobal.net
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