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Content-Type: text/plain
Organization: InterJinn
Date: Wed, 30 Apr 2008 01:07:26 -0400
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Subject: Re: [PHP-DEV] Class Properties in Interfaces?
From: robert@interjinn.com (Robert Cummings)


On Wed, 2008-04-30 at 00:27 -0400, Nathan Nobbe wrote:
> On Wed, Apr 30, 2008 at 12:05 AM, Robert Cummings 
>         
>         Abstract classes and interfaces are not the same. They are
>         used for
>         fundamentally different reasons. An interface is to enforce a
>         contract
>         for all implementations of the interface. Therefore if I were
>         to create
>         an interface with an interface property of x, then all
>         implementations
>         using that interface would know that property x exists and
>         could use it
>         thusly without having to check for it's existence. 
> 
> i am fully aware of the differences between interfaces and abstract
> classes.  however, if a public method is defined on any class,
> abstract or concrete, it may be used without checking by client code;
> i believe thats the entire point..
>  
>         Using an abstractclass is a hack, it's not sufficient for
>         enforcement, and you can't
>         combine multiple abstract classes as you can with interfaces.
> 
> abstract classes have their place.  primarily they are well suited for
> template method because some methods can be forced to be implemented
> by children and others can be optionally overridden.
> 
> and lastly, coming to multiple inheritance (for lack of better
> terminology); that is the only argument with any value for adding
> public attributes to the interface construct; however i am still not
> receptive to it.  from my perspective data is an implementation
> detail, period.

We are not talking about data here. We are talking about properties.
Data is assigned to a property which is akin to functionality being
assigned to a method. A property has all the features of the most simple
getter/setter method combination in one fell statement and without the
envelope overhead. As such, there is no reason why it could not be part
of the interface design.

Cheers,
Rob.

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