Re: Traits with interfaces
| From: | Pedro Magalhães | Date: | Fri, 02 Mar 2018 01:38:37 +0000 |
| Subject: | Re: Traits with interfaces | ||
| References: | 1 2 3 | Groups: | php.internals |
| Request: | Send a blank email to internals+get-101952@lists.php.net to get a copy of this message | ||
On Thu, Mar 1, 2018 at 11:04 PM, Rowan Collins <rowan.collins@gmail.com>
wrote:
>
> What *can* break an interface's contract is changing the *visibility* of
> the pasted method using "as protected" or "as private". This would need to
> be captured somehow while composing the class, probably producing a
> compile-time error, just as an explicit "implements" declaration would.
To add to that, the receiving class can simply replace the trait method. So
picking up from the same example:
<?php
interface Bobbable {
public function bob();
}
trait Bobber {
public function bob() {
echo "Bobbity";
}
}
class Bibble {
use Bobber { bob as bib; }
public function bob($arg) {
return $arg;
}
}
$b = new Bibble;
$b->bob();
$b->bib();
Bibble is no longer Bobbable.
Currently, not even an abstract method on a trait enforces anything on the
receiving class. See: https://bugs.php.net/bug.php?id=75449
With that said, I have started some work on "Implicit Interfaces". It
allows a trait to implement an interface in the sense that as long as any
class actually implements a given interface, that class passes the type
check (and instance_of() and ReflectionClass::implementsInterface(),
is_a(), ...). Basically allowing duck typing. It has some similarities to
https://wiki.php.net/rfc/protocol_type_hinting,
you can check the current
implementation on
https://github.com/pmmaga/php-src/compare/implicit-interfaces
Regards,
Pedro