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Date: Wed, 19 Sep 2018 13:38:07 +0100
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To: PHP internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] [RFC] [VOTE] Typed properties v2
From: rowan.collins@gmail.com (Rowan Collins)

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On Tue, 11 Sep 2018 at 08:05, Bob Weinand <bobwei9@hotmail.com> wrote:

> Hey,
>
> As announced, we are starting the vote on typed properties today.
>
> The voting period is two weeks, until sometime in the evening on Tuesday
> 25-09-2018.
>
> Please find the RFC at https://wiki.php.net/rfc/typed_properties_v2.
>


For the record, I still think we will come to regret allowing non-nullable
type hints without any constraint on the author of the class to initialise
them correctly. As proposed, the invalid state may only be detected when it
causes a runtime error in completely unrelated code.

I gather that the authors of C# are currently going through a painful
development phase to introduce better support for non-nullable types, and
having to include many compromises and handle many edge-cases because it
was not done earlier. I realise this case is not completely comparable, but
we have an opportunity to get this right first time, and not just take the
easy option.

I am therefore going to make one last plea: if we don't yet know how to
assert that complex types are initialised, do not allow them to be
non-nullable in the first version of this feature.

That is, allow `class Foo { public ?Foo $foo = null; }`, but not `class Foo
{ public Foo $foo; }`.

This would still be a huge improvement to the language, but leaves us free
to design additional features to prevent Unitialized Property Errors
becoming as hated as Null Pointer Exceptions in Java or C#.

Regards,
-- 
Rowan Collins
[IMSoP]

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