Larry Garfield wrote:
> On Friday 25 December 2009 8:02:06 pm Daniel Kolbo wrote:
>> Hello PHPers,
>>
>> I've learned that php doesn't support multiple inheritance, b/c if you
>> need multiple inheritance usually it is a sign you've got a design
>> imperfection...or so they say.
>>
>> Well, I'm using a framework (Codeigniter), and i'm extending the core
>> libraries. The trouble is, I want to also extend a second custom class,
>> and I don't want to change the core codeigniter class definitions as
>> this makes for awkward upgrades.
>>
>> I read about mixins - no thank you. i do not want to even think about
>> mixins as it looks like it would be the source of all debug hell...
>>
>> What's a programmer to do? Is the only option i am really left with to
>> duplicate the code in each class?
>>
>> Thanks,
>> dK
>> `
>
> If the original author of one or both libraries did their job right, they'll
> have provided an interface as well as the class that implements it. Then you
> can implement the interface and pass through to a new instance using
> composition.
>
> To wit:
>
> interface AInterface {
> public function doA();
> }
>
> interface BInterface {
> public function doB();
> }
>
> class A implements AInterface {
> public function doA() { ... }
> }
>
> class B implements BInterface {
> public function doB() { ... }
> }
>
> class YourClass extends A implements BInterface {
>
> protected $b;
>
> public function __construct() {
> $this->b = new B();
> }
>
> public function doB() {
> return $this->b->doB();
> }
> }
>
> (It would probably be a little more complicated in a real use case, but
> hopefully that should get you the idea.)
>
> Mind you, that presumes that the code you're dealing with provides interfaces
> and when doing type checking checks against the interfaces rather than the
> classes themselves. If they don't, you should file a bug against that base
> library as They're Doing It Wrong(tm).
>
Yes, I understand. Thanks for taking the time to write up the example.
Thanks,
dK
`
--
PHP General Mailing List (http://www.php.net/)
To unsubscribe, visit: http://www.php.net/unsub.php
