Re: [RFC] Interface Default Methods

On Thu, Jun 15, 2023 at 12:48 AM Levi Morrison via internals < internals@lists.php.net> wrote: > Hello, PHP Internals, > > I am moving my RFC for interface default methods to discussion: > https://wiki.php.net/rfc/interface-default-methods. > > This can be a useful tool for a few reasons: > 1. It can make implementing an interface easier when certain methods > can be implemented by other methods in the interface. For example, if > Countable had an isEmpty(): > bool method, it could be implemented > by doing $this->count() > 0. Of course, if an > implementation can be > more efficient, they are still free to implement it how they want. > 2. It can mitigate BC breaks in some cases. It's somewhat common for > authors to want to expand new methods onto existing interfaces over > time. Although this would still be a BC break, it moves it from a > massive change (every single implementor must add something, even if > it's a stub, or it will fail to compile) to a naming collision issue > only (only classes which already had a method of the same name will > fail to compile). > > There is prior art for this feature in both Java and C#. There may be > other languages, but I was aware of at least these. > > Note that the RFC links to a partial implementation. If there are two > or more interfaces with default methods of the same shape (name, args, > etc) and a class implements both interfaces and doesn't provide a > concrete implementation, which default implementation should be > chosen? There is a proposal for resolving this in some cases which is > modelled after Java's implementation, but it isn't implemented. > > Thank you for your time. I look forward to productive feedback. > > Levi Morrison > > -- > PHP Internals - PHP Runtime Development Mailing List > To unsubscribe, visit: https://www.php.net/unsub.php > > A question just occurred to me. Building up on the example of the RFC, is the following snippet valid and would it behave as expected? ``` interface Interface1 { function method1() { echo __METHOD__ . "\n"; } } interface Interface2 { function method1() { echo __METHOD__ . "\n"; } } class Class1 implements Interface1, Interface2 { function method1() { $result = Interface1::method1(); Interface2::method1(); return $result; } } $result = (new Class1())->method1(); ``` -- Marco Deleu