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Date: Tue, 25 Mar 2025 20:42:39 +0000
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Subject: Re: [PHP-DEV] [RFC] [Discussion] Never parameters
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From: imsop.php@rwec.co.uk ("Rowan Tommins [IMSoP]")



On 25 March 2025 18:14:21 GMT, Daniel Scherzer <daniel=2Ee=2Escherzer@gmai=
l=2Ecom> wrote:
>On Tue, Mar 25, 2025 at 11:01=E2=80=AFAM Rowan Tommins [IMSoP] <imsop=2Ep=
hp@rwec=2Eco=2Euk>
>wrote:
>
>>
>> I don't think the language should pretend to support something that it
>> doesn't
>>
>
>I don't see what the pretending is here - the engine supports declaring
>that a method must accept a parameter but makes no promises about the typ=
e
>of that parameter


I guess I just struggle to make such a declaration have any meaning; it fe=
els like a philosophical statement rather than a practical one=2E

Perhaps "pretend" was too strong in this case; I was mentally comparing it=
 to Python's unenforced type hints, which are only as reliable as comments;=
 and the occasional suggestion of doing the same in PHP with generic declar=
ations (built-in syntax with no built-in behaviour, which would be a hard N=
o from me)=2E

If I assert($foo instanceof InterfaceUsingNever), I can't actually do anyt=
hing useful with the promised method; I can only call it if I either read t=
he unenforced rules (e=2Eg=2E in docblocks and comments), or assert($foo in=
stanceof SomeConcreteImplementation) instead=2E


In the context of this thread, I can see that the examples are logically c=
onsistent, but if I just saw one in the wild, I'd just be scratching my hea=
d what it means to require that no values are acceptable=2E=20

And I've seen plenty of junior devs struggle with simple things like the d=
ifference between "nullable" and "optional", so I worry that making the typ=
e system too rich will lose PHP its reputation as an approachable language=
=2E


It's possible I'd react less strongly if a keyword was chosen that made mo=
re sense in context, although I'm not sure what that would be=2E

public function foo(int $a, must_override $b);

That's not quite right, I think=2E


Rowan Tommins
[IMSoP]