Hi Mathieu,
Am 18.11.2009 um 18:19 schrieb Mathieu Suen:
> Right!!
> I get confused with:
> $classNamme::getInstance();
>
> So you can easily inject dependency:
>
> class Foo {
>
> protected $emailer;
>
> public function __construct($emailClass) {
> $this->emailer= $emailClass;
> }
>
> public function bar() {
> // $email = new $this->emailer(); Of course not allowed
> $emailer = $this->emailer;
> $email = $emailer();
> // ...
> }
> }
Well, this won't work, because Foo surely doesn't have all the knowledge to
automatically resolve dependencies for the Email implementation. What if Email
needs some SMTP Service injected? Foo won't know.
Therefore it's much better to let some specialized Object Factory to do the
task. Letting Foo instantiate an Email would be asking a car to build its
engine. Better delegate that task to a factory ...
Cheers,
robert
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