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To: Rowan Collins <rowan.collins@gmail.com>, PHP Internals List
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Thread-Topic: [PHP-DEV] [RFC] [VOTE] Typed properties v2
Thread-Index: AdRQp96/B0Jv26t/gUu/Ri7Q725wuA==
Date: Thu, 20 Sep 2018 06:06:50 +0000
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Subject: Re: [PHP-DEV] [RFC] [VOTE] Typed properties v2
From: Christian.Stoller@leonex.de (Christian Stoller)

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> -----Urspr=FCngliche Nachricht-----
> Von: Rowan Collins
> Gesendet: Mittwoch, 19. September 2018 23:47
> An: PHP Internals List
> Betreff: Re: [PHP-DEV] [RFC] [VOTE] Typed properties v2
>
> On 19/09/2018 22:30, Marco Pivetta wrote:
> >
> > At least the approach without nullable properties will lead to a
> > Throwable when a read is attempted on an uninitialized object, which
> > is still better than nullability checks all over the place.
>
>
> Is it? Doesn't it just mean writing this:
>
> try {
> someFunction($object->propertyThatClaimsToBeNonNullable);
> } catch ( TypeError $e ) {
> ...
> }
>
> Instead of this:
>
> if ( ! is_null($object->propertyThatClaimsToBeNonNullable) ) {
> someFunction($object->propertyThatClaimsToBeNonNullable);
> } else {
> ...
> }
>
> For that matter, all I need to do is define someFunction as taking a
> non-nullable parameter, and I get the TypeError either way.
>
> Surely the point of a non-nullable property shouldn't be "it gives a
> slightly different error if it's not set", it should be "you don't have
> to worry about this not being set, because the language will enforce
> that somewhere". (And to cover your last point, that somewhere doesn't
> need to be the constructor, if requiring that is really such a big proble=
m.)
>
> Regards,
>
> --
> Rowan Collins
> [IMSoP]
>

Just an idea: If an object is initialized without having all non-nullable p=
roperties initialized, one could store the instantiation place, and give th=
is hint if an uninitialized property is accessed later.

Example:

// User.php

class User {
public Group $group;
}

// functions.php

function initUser() {
$user =3D new User(); // store this line and filename internally, because U=
ser::$group is uninitialized
return $user;
}

// index.php

$user =3D initUser();
echo $user->group->name; // Throws TypeError informing about access on unin=
itialized property and that it was initialized in file functions.php at lin=
e 3.


The TypeError still occurs but it makes it easy to find and fix the issue. =
And the same could be done with unsetting - save the place where an non-nul=
lable property has been unsetted and inform the user where it happened if t=
he unsetted property is accessed.

Best regards

Mit freundlichen Gr=FC=DFen aus Paderborn

Christian Stoller
Web-Entwicklung

LEONEX Internet GmbH
Technologiepark 6
33100 Paderborn
Tel: +49 (5251) 4142-526
Fax: +49 (5251) 4142-501


HRB 8694 AG Paderborn
Gesch=E4ftsf=FChrer: Stephan Winter

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