Re: [PHP] In what scenario an extension of a class is useful?

[Camilo Sperberg]

On Wed, Jun 23, 2010 at 02:58, Rene Veerman  wrote:

> inheritance of this kind is useful if you have common descendants for
> specific types of object
>

Nice thought. I imagine something like a DB wrapper, and implementing things
such as multiqueries and others on an extension based on the basic
connection made in the "original" class. Am I right on that?


> another use, is a modification of a certain component.
> descend it from the parent object and override the functions.
> you can do pre processing and post processing by overriding functions.
>

So, you're saying I can do something like this? :

class foo {
  function hello($a = '') {
echo 'hello '.$a;
  }
}

class bar extends foo {
  function hello($a = '') {
if (!empty($a)) parent::hello($a);
else echo 'bye world';
  }
}

$xx = new bar();
$xx->hello('asdf');
$xx->hello();

Which will print (hopefully, haven't test it yet):

hello asdf
bye world

That would be really a nice way of updating certain vital apps, without
breaking basic functionality.

Thanks for your answer :)

Greetings !!

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RE: [PHP] In what scenario an extension of a class is useful?

[Daevid Vincent]

Priceless. Could also be extended applied to babies too. ;-p

object babies extends mammal (
  function eat (milk $food)
 )


ROFL.

> -Original Message-
> From: Rene Veerman [mailto:rene7...@gmail.com] 
> Sent: Tuesday, June 22, 2010 11:58 PM
> 
> object mammal (
>  function eat (mixed $food)
>  function shit ()
>  function sleep()
> )


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Re: [PHP] In what scenario an extension of a class is useful?

[Rene Veerman]

inheritance of this kind is useful if you have common descendants for
specific types of object

object mammal (
 function eat (mixed $food)
 function shit ()
 function sleep()
)

object carnivore extends mammal (
  function eat (meat $food)
 )

object herbivore extends mammal (
  function eat (veggies $food)
)

now you can call the descendant mammal->eat() from carnivore->eat()
and herbivore->eat() to process foods.
their mammal->vitality settings (lets say its a subproperties-array)
will be updated, with custom handling taking place in carnivore->eat()
and herbivore->eat() while mammal->eat() is likely to update those
vitality properties..

another use, is a modification of a certain component.
descend it from the parent object and override the functions.
you can do pre processing and post processing by overriding functions.

On Wed, Jun 23, 2010 at 5:58 AM, Camilo Sperberg  wrote:
> Hello everybody :)
>
> I'm really intrigued on something... In what real-world applications could
> an extension of a class be really useful?
>
> Let's say I have this code:
>
> class foo {
>  function hello_world($a) {
>    echo 'foo hello world';
>  }
>
>  function bye_world() {
>    echo 'foo bye world';
>  }
> }
>
> class bar extends foo {
>  function hello_world($a,$b) {
>    echo 'bar hello world';
>  }
> }
>
> Point 1: Why not just overwrite the hello_world method in the foo class in
> the first place? Wouldn't that save code and possible incompatibility or
> consistency issues between the code you've already written and between the
> two classes ? (Assuming that you do some things based on the $a and $b
> values).
>
> Point 2: On the other hand, maybe I could apply different operations to both
> (e.g.: return 1 in foo and 2 in bar), without breaking the basic
> functionality already achieved in the foo class. (Maybe considering that I
> want to apply an update or patch to an already existing application,
> however, is this is the scenario, I should always fix the old code wherever
> I invoke the foo class which returns us to point 1).
>
> Point 3: Ok, maybe I don't want a specific class to be so huge and I
> separate it into "pieces" of classes. But then again, wouldn't it be simpler
> to just save some code and keeping only one file with the entire class?
>
> Is it just that or do I miss something else? I'm not saying it is useless,
> it sounds indeed fantastic to work with... but I just can't imagine in what
> real-world cases this would be useful.
>
> Greetings !
>
> --
> Mailed by:
> UnReAl4U - unreal4u
> ICQ #: 54472056
> www1: http://www.chw.net/
> www2: http://unreal4u.com/
>



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