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Date: Thu, 9 Jan 2020 15:27:03 +0100
Message-ID: <CAH0Uv3HLpO0ov=2pPG3fQcbXXCQBRmp6uh+2=pd9OFeYhf-oew@mail.gmail.com>
To: Larry Garfield <larry@garfieldtech.com>
Cc: php internals <internals@lists.php.net>
Content-Type: multipart/alternative; boundary="0000000000002dea61059bb5cef2"
Subject: Re: [PHP-DEV] [RFC] Static return type
From: andreas@dqxtech.net (Andreas Hennings)

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On Thu, 9 Jan 2020 at 15:22, Andreas Hennings <andreas@dqxtech.net> wrote:

> > However, $this is not a real type, and it is unclear what the advantage
> of specifying $this rather than static would be from a type system level
> perspective.
>
> Perhaps not from a "type system level", but from a more broad "enforced
> contract" level.
> E.g. IDEs or code inspection tools can warn if a method will not return
> $this.
> This also means recursive calls also need to return $this instead of
> static.
>

> class C {
>   function foo(): static {
>     return clone $this;
>   }
>   function bar(): $this {
>     return $this->foo();  // IDE can complain.
>   }
> }
>


Of course this ": $this" could be added later in the future.
But this would have the risk that people start adding ": static" on methods
that really return $this.
This would cause confusion if later some packages introduce ": $this", but
others are still behind.

namespace oldpackage;
class B {
  function foo(): static { // Actually returns $this, not just static.
    return $this;
  }
}

namespace newpackage;
class C extends B {
  function foo(): $this {
    return parent::foo();  // Should the IDE complain?
  }
}


>
>
> On Thu, 9 Jan 2020 at 15:07, Larry Garfield <larry@garfieldtech.com>
> wrote:
>
>> On Wed, Jan 8, 2020, at 5:42 AM, Nikita Popov wrote:
>> > Hi internals,
>> >
>> > I would like to propose the following RFC, which allows using "static"
>> as a
>> > return type:
>> >
>> > https://wiki.php.net/rfc/static_return_type
>> >
>> > While I'm personally not a fan of late static binding, we do support it
>> and
>> > people do use it quite heavily, so I think we should also support it in
>> > return types.
>> >
>> > Regards,
>> > Nikita
>>
>>
>> Is "squee!" an appropriate response on the list?  For interface authors
>> this is a huge deal.
>>
>> --Larry Garfield
>>
>> --
>> PHP Internals - PHP Runtime Development Mailing List
>> To unsubscribe, visit: http://www.php.net/unsub.php
>>
>>

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