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Subject: Re: [PHP-DEV] Non-nullable properties
From: rowan.collins@gmail.com (Rowan Collins)

On 16 July 2018 00:52:53 BST, Dan Ackroyd <danack@basereality=2Ecom> wrote:
>On 14 July 2018 at 14:09, Rowan Collins <rowan=2Ecollins@gmail=2Ecom>
>wrote:
>> Hi all,
>>
>> The current RFC proposes the next simplest solution, which is to
>allow non-nullable types, and trust the user to initialise them before
>use=2E
>
>
>From the RFC:
>> If a typed property does not have a default value, no implicit null
>default value is implied (even if the property is nullable)=2E
>> Instead, the property is considered to be uninitialized=2E Reads from
>uninitialized properties will generate a TypeError
>
>Are you miss-quoting the RFC?
>
>Because those two sentences are completely different=2E


There's no contradiction here; throwing an error when a property is *read*=
 is not the same as enforcing that it always has a valid value=2E

Compare with parameter type hints:

function thing(Foo $foo) {
     $foo->bar();
}
thing(null);

The line that throws the error is thing(null), and that's the line that ne=
eds fixing=2E We don't allow the parameter in, and then throw an error when=
 trying to use it, leaving the user to work out how it got there; that woul=
d defeat the purpose of the type hint=2E

The difference between "uninitialised" and "null" is largely irrelevant: e=
ither way, the only way to run code like $foo->bar->baz() safely is to test=
 the property before use=2E Or, to simply trust the user not to make a mist=
ake=2E

Regards,

--=20
Rowan Collins
[IMSoP]