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Date: Fri, 14 Mar 2025 18:57:14 +0200
To: Jorg Sowa <jorg.sowa@gmail.com>
Cc: php internals <internals@lists.php.net>
Subject: Re: [PHP-DEV] [RFC] [Discussion] Optional interfaces
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From: juris@glaive.pro (Juris Evertovskis)

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On 2025-03-14 16:04, Jorg Sowa wrote:

> Hello Juris, There is some uncertainty for me on how this approach 
> would work with namespaces.
> 
> Let's get this example:
> https://3v4l.org/bI1Rj
> 
> I would expect to get the error message that I forgot to insert `use 
> Stringable;`.
> But with your idea everything is fine. I don't like such ambiguity and 
> I worry it may bring some confusion to developers.
> 
> Kind regards, Jorg

Hi Jorg,

You are correct. We can't really distinguish whether an interface is 
absent because the dependency is absent or because the name was 
mistyped.

In practice I would not expect this to be a big issue. Adding a 
?OptionalInterface would be a deliberate action when your objects needs 
to pass a specific type check. In case of a typo the type check will 
fail and the object will be rejected by the consumer.

I admit that it's not as nice as a compile-time error, but my point is 
that the typo would still be easy to notice as it would break the whole 
purpose of that interface implementation.

BR,
Juris
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<p id=3D"reply-intro">On 2025-03-14 16:04, Jorg Sowa wrote:</p>
<blockquote type=3D"cite" style=3D"padding: 0 0.4em; border-left: #1010ff 2=
px solid; margin: 0">
<div id=3D"replybody1">
<div dir=3D"ltr">
<div>
<div>
<div>
<div>
<div>Hello Juris,</div>
There is some uncertainty for me on how this approach would work with names=
paces.<br /><br /></div>
Let's get this example:<br /><a href=3D"https://3v4l.org/bI1Rj" target=3D"_=
blank" rel=3D"noopener noreferrer">https://3v4l.org/bI1Rj</a><br /><br /></=
div>
I would expect to get the error message that I forgot to insert `use String=
able;`. <br />But with your idea everything is fine. I don't like such ambi=
guity and I worry it may bring some confusion to developers.<br /><br /></d=
iv>
Kind regards,</div>
Jorg</div>
</div>
</blockquote>
<p>Hi Jorg,</p>
<p>You are correct. We can't really distinguish whether an interface is abs=
ent because the dependency is absent or because the name was mistyped.</p>
<p>In practice I would not expect this to be a big issue. Adding a ?Optiona=
lInterface would be a deliberate action when your objects needs to pass a s=
pecific type check. In case of a typo the type check will fail and the obje=
ct will be rejected by the consumer.</p>
<p>I admit that it's not as nice as a compile-time error, but my point is t=
hat the typo would still be easy to notice as it would break the whole purp=
ose of that interface implementation.</p>
<p>BR,<br />Juris</p>

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