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Date: Thu, 20 Feb 2025 16:54:29 +0100
Message-ID: <CAMzRQTda1_MMzC-SWRoxRmvssSUq3Ty5s2a8T4K8j8Bz90kY-g@mail.gmail.com>
Subject: Re: [PHP-DEV] RFC: Marking return values as important (#[\NoDiscard])
To: Rob Landers <rob@bottled.codes>
Cc: php internals <internals@lists.php.net>
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From: volker@tideways-gmbh.com (Volker Dusch)

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> On Wed, Feb 12, 2025 at 9:57=E2=80=AFPM Rob Landers <rob@bottled.codes> w=
rote:
Hey Rob,

Sorry for writing the mail again, I just noticed I forgot to include the
list on my first reply to you, also corrected a mistake in the second
paragraph.

> There will eventually be a php 9, where BC changes will be possible.

I don't assume PHP will change the behavior of widely used core functions
to throw exceptions in PHP 9 as the BC impact will be colossal, hurting
adoption. Or am I misunderstanding you here?

The point that there might be arguments over usage in internal code is why
we went with an "only if it is a clear problem, especially when the
function has important side effects" policy to avoid this. There are not a
too many examples in core, more in userland.

> I have to stop you here. It is absolutely NOT safe and reasonable to
ignore the output of array_pop. You popped it for a reason. If you just
care about removing the last element, then you should use unset. Unset
gives the intention. If I review code with array_pop, I=E2=80=99ll spend qu=
ite a
bit of time checking that it was intentionally ignoring the return value
(and leave a comment of the same, asking to use unset instead).

There are plenty of codebases where array_pop is used for this reason.
Identifying the last element of a php array.
`unset($foo[array_key_last($foo)]);` is only possible since 7.3 and not
widely used. array_pop is also shorter and faster for the same effect (when
used on unknown array shapes ofc). The examples are plenty
https://github.com/search?q=3Drepo%3AWordPress%2FWordPress%20array_pop&type=
=3Dcode

Regards,
Volker

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<div dir=3D"ltr"><div dir=3D"ltr"><div dir=3D"ltr">&gt; On Wed, Feb 12, 202=
5 at 9:57=E2=80=AFPM=C2=A0<span class=3D"gmail-il">Rob</span>=C2=A0Landers =
&lt;<span class=3D"gmail-il">rob</span>@bottled.codes&gt; wrote:</div><div =
dir=3D"ltr">Hey=C2=A0<span class=3D"gmail-il">Rob</span>,<span class=3D"gma=
il-im" style=3D"color:rgb(80,0,80)"><div><br></div><div>Sorry for writing t=
he mail again, I just noticed I forgot to include the list on my first repl=
y to you, also corrected a mistake=C2=A0in the second paragraph.</div><div>=
<br></div><div>&gt; There will eventually be a php 9, where BC changes will=
 be possible.</div><div><br></div></span><div>I don&#39;t assume PHP will c=
hange the behavior of widely used core functions to throw exceptions in PHP=
 9 as the BC impact will be colossal, hurting adoption. Or am I misundersta=
nding you here?</div><div><br></div><div>The point that there might be argu=
ments over usage in internal=C2=A0code is why we went with an &quot;only if=
 it is a clear problem, especially when the function has important side eff=
ects&quot; policy to avoid this. There are not a too many examples in core,=
 more in userland.=C2=A0</div><span class=3D"gmail-im" style=3D"color:rgb(8=
0,0,80)"><div><br></div><div>&gt; I have to stop you here. It is absolutely=
 NOT safe and reasonable to ignore the output of array_pop. You popped it f=
or a reason. If you just care about removing the last element, then you sho=
uld use unset. Unset gives the intention. If I review code with array_pop, =
I=E2=80=99ll spend quite a bit of time checking that it was intentionally i=
gnoring the return value (and leave a comment of the same, asking to use un=
set instead).</div><div><br></div></span><div>There are plenty of codebases=
 where array_pop is used for this reason. Identifying the last element of a=
 php array. `unset($foo[array_key_last($foo)]);` is only possible since 7.3=
 and not widely used. array_pop is also shorter and faster for the same eff=
ect (when used on unknown array shapes ofc). The examples are plenty=C2=A0<=
a href=3D"https://github.com/search?q=3Drepo%3AWordPress%2FWordPress%20arra=
y_pop&amp;type=3Dcode" target=3D"_blank">https://github.com/search?q=3Drepo=
%3AWordPress%2FWordPress%20array_pop&amp;type=3Dcode</a></div><div><br></di=
v><div>Regards,</div><div>Volker</div></div></div><br></div>

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