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Date: Tue, 20 Aug 2024 23:56:50 +0200
Message-ID: <CAMkukMyx4Lx4DmezSD5H_LrGdyKA5_U6qN7Ht4_AORYrsvSqNQ@mail.gmail.com>
Subject: Re: [PHP-DEV] [Concept] Flip relative function lookup order (global,
 then local)
To: Ilija Tovilo <tovilo.ilija@gmail.com>
Cc: PHP internals <internals@lists.php.net>
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From: hello@faizanakram.me (Faizan Akram Dar)

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On Tue, Aug 20, 2024 at 11:34=E2=80=AFPM Ilija Tovilo <tovilo.ilija@gmail.c=
om>
wrote:

> Hi Levi
>
> On Tue, Aug 20, 2024 at 5:14=E2=80=AFPM Levi Morrison
> <levi.morrison@datadoghq.com> wrote:
> >
> > I have long been in favor of a larger BC break with better language
> > consistency. Class lookup and function lookup with respect to
> > namespaces should be treated the same. The difficulty is getting a
> > majority of people to vote yes for this. Keep in mind that qualifying
> > every global function is annoying but probably can be somewhat
> > automated, and will bring better performance. So again, this improves
> > the existing code even without upgrading.
> >
> > Yes, there would be complaints about it. Yes, there are probably some
> > people or projects who wouldn't upgrade. I don't particularly care, as
> > there are increasingly more operating systems and companies providing
> > LTS support for long periods of time. Probably Zend.com will offer LTS
> > support for the last PHP 8.X release, and possibly there will be some
> > distro which also has it. I believe it's the right thing to do
> > because:
> >
> >  1. It's faster.
> >  2. It enables function autoloading in a similar manner to class
> autoloading.
> >  3. It's more consistent, and simpler to teach and maintain.
> >
> > It's rare that you get all of these together, often you have to make
> > tradeoffs within them.
>
> The approach I originally proposed also solves 1. and 2. (mostly) with
> very little backwards incompatibility. Consistency is absolutely
> something to strive for, but not at the cost of breaking most PHP
> code.
>
> To clarify on 2.: The main issue with function autoloading today is
> that the engine needs to trigger the autoloader for every unqualified
> call to global functions, given that the autoloader might declare the
> function in local scope. As most unqualified calls are global calls,
> this adds a huge amount of overhead.
>
> Gina solved this in part by aliasing the local function to the global
> one after the first lookup. However, that still means that the
> autoloader will trigger for every new namespace the function is called
> in, and will also pollute the function table.
>
> Reversing the lookup order once again avoids local lookup when calling
> global functions in local scope, which also means dodging the
> autoloader. The caveat is that calling local functions in local scope
> triggers the autoloader on first encounter, but at least it can be
> marked as undeclared in the symbol table once, instead of in every
> namespace, which also means triggering the autoloader only once.
>
> Ilija
>

Hi,

I completely agree with Levi's perspective, aligning class and function
lookup with respect
to namespaces seems a very sensible option.
It will improve consistency and pave the road for autoloading functions
without quirks.

The impact of fixing functions look up is overstated. For instance,
PHP-CS-Fixer can add
 "global namespace qualifiers" to all global functions in a matter of
minutes, it is not like
 people have to go through code and change it manually.


To ease the transition, PHP can ship a small fixer with the next PHP
version for changing
 global function usage (prepending \ or adding use statements) and be done
with the
inconsistency once and for all.


Kind regards,
Faizan

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<div dir=3D"ltr"><div dir=3D"ltr"><br></div><br><div class=3D"gmail_quote">=
<div dir=3D"ltr" class=3D"gmail_attr">On Tue, Aug 20, 2024 at 11:34=E2=80=
=AFPM Ilija Tovilo &lt;<a href=3D"mailto:tovilo.ilija@gmail.com">tovilo.ili=
ja@gmail.com</a>&gt; wrote:<br></div><blockquote class=3D"gmail_quote" styl=
e=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);paddin=
g-left:1ex">Hi Levi<br>
<br>
On Tue, Aug 20, 2024 at 5:14=E2=80=AFPM Levi Morrison<br>
&lt;<a href=3D"mailto:levi.morrison@datadoghq.com" target=3D"_blank">levi.m=
orrison@datadoghq.com</a>&gt; wrote:<br>
&gt;<br>
&gt; I have long been in favor of a larger BC break with better language<br=
>
&gt; consistency. Class lookup and function lookup with respect to<br>
&gt; namespaces should be treated the same. The difficulty is getting a<br>
&gt; majority of people to vote yes for this. Keep in mind that qualifying<=
br>
&gt; every global function is annoying but probably can be somewhat<br>
&gt; automated, and will bring better performance. So again, this improves<=
br>
&gt; the existing code even without upgrading.<br>
&gt;<br>
&gt; Yes, there would be complaints about it. Yes, there are probably some<=
br>
&gt; people or projects who wouldn&#39;t upgrade. I don&#39;t particularly =
care, as<br>
&gt; there are increasingly more operating systems and companies providing<=
br>
&gt; LTS support for long periods of time. Probably Zend.com will offer LTS=
<br>
&gt; support for the last PHP 8.X release, and possibly there will be some<=
br>
&gt; distro which also has it. I believe it&#39;s the right thing to do<br>
&gt; because:<br>
&gt;<br>
&gt;=C2=A0 1. It&#39;s faster.<br>
&gt;=C2=A0 2. It enables function autoloading in a similar manner to class =
autoloading.<br>
&gt;=C2=A0 3. It&#39;s more consistent, and simpler to teach and maintain.<=
br>
&gt;<br>
&gt; It&#39;s rare that you get all of these together, often you have to ma=
ke<br>
&gt; tradeoffs within them.<br>
<br>
The approach I originally proposed also solves 1. and 2. (mostly) with<br>
very little backwards incompatibility. Consistency is absolutely<br>
something to strive for, but not at the cost of breaking most PHP<br>
code.<br>
<br>
To clarify on 2.: The main issue with function autoloading today is<br>
that the engine needs to trigger the autoloader for every unqualified<br>
call to global functions, given that the autoloader might declare the<br>
function in local scope. As most unqualified calls are global calls,<br>
this adds a huge amount of overhead.<br>
<br>
Gina solved this in part by aliasing the local function to the global<br>
one after the first lookup. However, that still means that the<br>
autoloader will trigger for every new namespace the function is called<br>
in, and will also pollute the function table.<br>
<br>
Reversing the lookup order once again avoids local lookup when calling<br>
global functions in local scope, which also means dodging the<br>
autoloader. The caveat is that calling local functions in local scope<br>
triggers the autoloader on first encounter, but at least it can be<br>
marked as undeclared in the symbol table once, instead of in every<br>
namespace, which also means triggering the autoloader only once.<br>
<br>
Ilija<br></blockquote><div><br></div><div>Hi,<br><br>I completely agree wit=
h Levi&#39;s perspective, aligning class and function lookup with respect=
=C2=A0</div><div>to namespaces seems a very sensible option.</div><div>It w=
ill improve consistency and pave the road for autoloading functions without=
 quirks.</div><div><br></div><div>The impact of fixing functions look up is=
 overstated. For instance, PHP-CS-Fixer can add</div><div>=C2=A0&quot;globa=
l namespace qualifiers&quot; to all global functions in a matter of minutes=
, it is not like</div><div>=C2=A0people have to go through code and change =
it manually.</div><div><br><br>To ease the transition, PHP can ship a small=
 fixer with the next PHP version for changing</div><div>=C2=A0global functi=
on usage (prepending \ or adding use statements) and be done with the=C2=A0=
</div><div>inconsistency once and for all.<br><br><br>Kind regards,<br>Faiz=
an</div><div><br>=C2=A0</div></div></div>

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