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Date: Thu, 26 Mar 2026 08:51:31 +0100
To: "Dan Liebner" <dliebner@gmail.com>, "Aleksander Machniak" <alec@alec.pl>
Cc: internals@lists.php.net
Message-ID: <5c6d66c4-4c17-444e-bb0a-2b8c4759d2db@app.fastmail.com>
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 <CAMXcktOAwUvQ0sBs9vpbG-L2AHqbaoy=fwKfKibVdSxtJW1ygA@mail.gmail.com>
References: <tencent_D07F06F5B18B1450B922355C06A3ED7E4107@qq.com>
 <e3ea7fd0-3fa1-4f6f-a3a6-a7cc692d9d5f@alec.pl>
 <CAMXcktOAwUvQ0sBs9vpbG-L2AHqbaoy=fwKfKibVdSxtJW1ygA@mail.gmail.com>
Subject: Re: [PHP-DEV] [RFC] Four Pragmatic Directions for PHP: Simplicity, Arrays,
 Performance, Concurrency
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From: rob@bottled.codes ("Rob Landers")

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I used to have a really long and interesting blog post on PHP arrays abo=
ut this:

On Tue, Mar 24, 2026, at 12:04, Dan Liebner wrote:
> I agree with this sentiment.
>=20
> My main gripe with PHP 8 is that undefined array key accesses trigger =
a warning. There is no solution to this that doesn't require destroying =
the readability of a legacy codebase or using some hacky global error ha=
ndler.
>=20
> I think the direction should always have been this: undefined array ke=
y accesses should simply return null by default.

And then my disk caught on fire and it was never archived. TL;DR: treati=
ng PHP arrays as an infinite field of nulls has some very interesting ma=
thematical properties. No other language on earth gave you this.

Practical usecases were ways to effectively "cheat" on some np-hard and =
np-complete problems, like subset-sum, knapsack, Hamiltonian Path, etc. =
This warning (and eventual removal of this property) makes these "cheats=
" no longer possible in PHP and constrained just like every other langua=
ge on the planet.

=E2=80=94 Rob
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<!DOCTYPE html><html><head><title></title></head><body><div>I used to ha=
ve a really long and interesting blog post on PHP arrays about this:</di=
v><div><br></div><div>On Tue, Mar 24, 2026, at 12:04, Dan Liebner wrote:=
</div><blockquote type=3D"cite" id=3D"qt" style=3D""><div dir=3D"ltr"><d=
iv>I agree with this sentiment.</div><div><br></div><div>My main gripe w=
ith PHP 8 is that undefined array key accesses trigger a warning. There =
is no solution to this that doesn't require destroying the readability o=
f a legacy codebase or using some hacky global error handler.</div><div>=
<br></div><div>I think the direction should always have been this: undef=
ined array key accesses should simply return null by default.</div></div=
></blockquote><div><br></div><div>And then my disk caught on fire and it=
 was never archived. TL;DR: treating PHP arrays as an infinite field of =
nulls has some very interesting mathematical properties. No other langua=
ge on earth gave you this.</div><div><br></div><div>Practical usecases w=
ere ways to effectively "cheat" on some np-hard and np-complete problems=
, like subset-sum, knapsack, Hamiltonian Path, etc. This warning (and ev=
entual removal of this property) makes these "cheats" no longer possible=
 in PHP and constrained just like every other language on the planet.</d=
iv><div><br></div><div id=3D"sig121229152">=E2=80=94 Rob</div></body></h=
tml>
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