> On Jun 24, 2024, at 11:17 PM, Stephen Reay <php-li...@koalephant.com> wrote:
>
>
>
>> On 25 Jun 2024, at 09:22, Mike Schinkel <m...@newclarity.net> wrote:
>>
>>> On Jun 24, 2024, at 3:53 AM, Ayesh Karunaratne <ayesh@php.watch
>>> <mailto:ayesh@php.watch>> wrote:
>>> - Why is it a class-level flag and not an attribute (similar to the
>>> `#[Override]` attribute in PHP 8.3) ?
>>
>> From my perspective that would create much confusion among every PHP
>> developer who has not committed to memory when to use `static` as a class
>> keyword and when to use it as an attribute.
>>
>> Given the concept already exists in keywords I would strongly argue that it
>> makes no sense to introduce as an attributes in core PHP.
>>
>> Attributes are great for concepts new to PHP, IMO, but not for existing
>> concepts already part of PHP implemented with keywords.
>>
>>> On Jun 24, 2024, at 4:27 AM, Claude Pache <claude.pa...@gmail.com
>>> <mailto:claude.pa...@gmail.com>> wrote:
>>> * The main purpose of the `abstract` keyword is to prevent a class to be
>>> instantiated, which (in case of static class) is more semantically
>>> described by the `static` marker. Beyond that, it just allows to declare a
>>> method that, if implemented by a subclass, should have a compatible
>>> signature. Most notably, it does not prevent the other static members of
>>> the class to be used directly.
>>
>> Given a primary purpose for being able to declare a class `static` is to
>> signal intent, disallowing `abstract static` classes seems at odds with that
>> goal.
>>
>> Of course it is currently true that `static` methods of `abstract` classes
>> can be called from outside a class and its class hierarchy, so if we allow
>> declaring `abstract static` classes then it would never in the future be
>> possible to lock down calls of `static` methods to those `abstract` classes.
>>
>> So IMO it would be better to disallow calling `static` methods from outside
>> a declared `abstract static` class and its inheritance hierarchy as part of
>> this RFC. That would be backward compatible since there are currently no
>> classes that are declared in that manner. Doing otherwise would force those
>> who want to declare a class as both `static` and `abstract` to have to make
>> a choice rather than being able to signal their full intent. Which brings us
>> back to the "implied" vs. "explicitly declared" bifurcation I mentioned in a
>> prior email.
>>
>> BTW, I am assuming it is technically possible to disallow calling methods
>> for classes declared both `abstract` and `static` without considerable
>> difficulty in implementation and without creating a significant drain on
>> performance.
>>
>> -Mike
>>
>> P.S. I would argue the same for `readonly static` properties, but as that
>> seems those would require an involved discussion about the exact rules to
>> implement I am demurring on that topic.
>
> Hi Mike,
>
>
>> So IMO it would be better to disallow calling `static` methods from outside
>> a declared `abstract static` class
>
> Can you explain what you mean by this, or more specifically the "why". What
> (implied wrong/bad) scenario are you trying to prevent, by disallowing a
> static method on an abstract class to be called?
>
> As you point out, it's already possible to call (public) static methods on
> abstract classes, the same as it's possible to call (public) static methods
> without instantiating a regular class.
>
> So why should static abstract classes be different? If the static method
> shouldn't be called publicly, it shouldn't be public. Are you suggesting that
> public static methods shouldn't be callable on *any* abstract class? If so,
> this sounds like a huge BC break, and if not, it sounds like a confusing
> "if-then-but-why" scenario.
Thank you for the question.
I was not specifically advocating `static` methods to be disallowed to be
called on an `abstract` class. I was instead addressing the desire by another
list member to have classes declared `static` not also be able to be declared
`abstract.` That person made the argument that if 'abstract static` did not
actually have any effect then it should not be allowed by the RFC.
What affect are we talking about? If it is both `abstract` and `static` then
it would seem to me the only effect such a declaration could have would be to
disallow the calling of static methods using the named abstract static class,
e.g.:
abstract static class Base {
static public foo() {
echo "foo() called\n"
}
}
static class Concrete extends Base {}
Concrete::foo(); // works
Base::foo(); // fails
My only real argument for disallowing static method calls on abstract static
classes is that if we didn't do so initially we would never be able to disallow
because of BC.
In summary, my argument was really only about ensuring we allow "abstract
static" declaration so developers can signal intent and also to address the
objections of the other list member. But if given the option, I think it would
be good to disallow calling static methods on abstract static classes if only
to reserve the right to allow in the future vs. closing that door immediately.
Still, that latter is not the hill for me to die on.
> I agree that the `static` keyword is a much better fit here, however there is
> one other aspect here that may come into it (as much as I prefer the keyword
> approach): the Attribute approach is backwards compatible (with a polyfill)
> to let code using this feature also run on previous PHP releases. Given that
> this is mostly intended as a way to signal intent about a pattern that's
> already in use, this may be significant for library authors.
Well, as previously stated, I think that would be confusing.
Though I do see your reasoning for wanting it to be an attribute. However...
> Personally (as a library author) I don't think that ability is worth the
> weirdness of an attribute vs a keyword, but it may be more important for
> others who are voting, and I'd rather have the feature with slightly odd
> syntax rather than not at all.
I too am not convinced that the ongoing confusion would be better than the
temporary need to support older versions of PHP with the same source file.
Given that a build step could address the syntax there are certainly other new
language features that require developers to bifurcate their libraries to
support different versions, why make this one unique?
That said, it could be a voting option for the RFC?
-Mike
