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Date: Thu, 15 May 2025 11:41:21 +0200
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Subject: Re: [PHP-DEV] Module or Class Visibility, Season 2
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From: rob@bottled.codes ("Rob Landers")

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On Thu, May 15, 2025, at 10:35, Rob Landers wrote:
> On Thu, May 15, 2025, at 10:11, Rowan Tommins [IMSoP] wrote:
>>=20
>>=20
>> On 14 May 2025 22:27:32 BST, Rob Landers <rob@bottled.codes> wrote:
>> >
>> >As written, that simply isn't possible in PHP because there is only =
one class allowed with a given name. Names of classes are global. I don'=
t think this has to be the case, though. Different languages take differ=
ent approaches to this. For example, JavaScript allows each module to "c=
lose over" its dependencies so each module can import its own version of=
 dependencies.
>>=20
>> I would say that JavaScript doesn't just *allow* this, as an added fe=
ature, it *requires* it, as a fundamental design decision:=20
>>=20
>> - In JavaScript, Python, etc, when you declare a function or class, y=
ou are creating an anonymous object, and assigning it to a local variabl=
e. Code reuse requires you to pass that object around.
>> - In PHP, Java, C#, etc, when you declare a function or class, you ar=
e adding a permanent named item to a global list. Code reuse is about kn=
owing the global names of things.=20
>>=20
>> It's worth noting that JavaScript didn't need to add *any* features t=
o make NPM,  Bower, etc work; everything they do is based on the fact th=
at declarations are objects which can be passed around at will.=20
>>=20
>> That's why I don't think "JavaScript can do it" is relevant, because =
the *way* JavaScript does it is impossible in PHP. We're much better off=
 looking at how *PHP* works, and what problems we're actually trying to =
solve.=20
>>=20
>> And that in turn is why I was reaching for Linux containers as an alt=
ernative analogy, to think about the problem without jumping to the wron=
g solution.
>>=20
>> Rowan Tommins
>> [IMSoP]
>>=20
>=20
> Hey Rowan,
>=20
> When working on nested classes, I did spend quite a bit of time tinker=
ing with alternative implementations. One of those implementations was h=
aving the ability for classes to have their own class tables (both liter=
ally and emulated via name mangling) which would have allowed for classe=
s to have private classes that could share names with external classes. =
This turned out to be an utter disaster of an idea for many reasons. Nam=
ely, PHP doesn't really have any native support for shadowing names. Sur=
e, there is aliasing via use statements, but that only works for classes=
 outside the current namespace. As long as we can guarantee that a modul=
e acts as a special namespace (under the hood), the only potential for c=
ollisions will be in the module itself.
>=20
> All that is to say that I don't think comparing PHP to JavaScript is a=
ppropriate when considering modules. JavaScript doesn't have types, so I=
 can pass you an EpicStringV2 when you're expecting an EpicStringV1, and=
 as long as my EpicStringV2 has the right prototypical behavior and data=
, it will work just fine. PHP is typed, and fairly strongly typed. There=
 is effectively no way to have multiple versions of the same type runnin=
g around a codebase and pass type checks. Changing this would be effecti=
vely impossible and probably unsound from a type-theory perspective.
>=20
> =E2=80=94 Rob

Haha, I just reread your email and realized we're basically saying the s=
ame thing (I think?).

=E2=80=94 Rob
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<!DOCTYPE html><html><head><title></title></head><body><div><br></div><d=
iv><br></div><div>On Thu, May 15, 2025, at 10:35, Rob Landers wrote:</di=
v><blockquote type=3D"cite" id=3D"qt" style=3D""><div>On Thu, May 15, 20=
25, at 10:11, Rowan Tommins [IMSoP] wrote:</div><blockquote type=3D"cite=
" id=3D"qt-qt" style=3D""><div><br></div><div><br></div><div>On 14 May 2=
025 22:27:32 BST, Rob Landers &lt;<a href=3D"mailto:rob@bottled.codes">r=
ob@bottled.codes</a>&gt; wrote:</div><div>&gt;</div><div>&gt;As written,=
 that simply isn't possible in PHP because there is only one class allow=
ed with a given name. Names of classes are global. I don't think this ha=
s to be the case, though. Different languages take different approaches =
to this. For example, JavaScript allows each module to "close over" its =
dependencies so each module can import its own version of dependencies.<=
/div><div><br></div><div>I would say that JavaScript doesn't just *allow=
* this, as an added feature, it *requires* it, as a fundamental design d=
ecision:&nbsp;</div><div><br></div><div>- In JavaScript, Python, etc, wh=
en you declare a function or class, you are creating an anonymous object=
, and assigning it to a local variable. Code reuse requires you to pass =
that object around.</div><div>- In PHP, Java, C#, etc, when you declare =
a function or class, you are adding a permanent named item to a global l=
ist. Code reuse is about knowing the global names of things.&nbsp;</div>=
<div><br></div><div>It's worth noting that JavaScript didn't need to add=
 *any* features to make NPM,&nbsp; Bower, etc work; everything they do i=
s based on the fact that declarations are objects which can be passed ar=
ound at will.&nbsp;</div><div><br></div><div>That's why I don't think "J=
avaScript can do it" is relevant, because the *way* JavaScript does it i=
s impossible in PHP. We're much better off looking at how *PHP* works, a=
nd what problems we're actually trying to solve.&nbsp;</div><div><br></d=
iv><div>And that in turn is why I was reaching for Linux containers as a=
n alternative analogy, to think about the problem without jumping to the=
 wrong solution.</div><div><br></div><div>Rowan Tommins</div><div>[IMSoP=
]</div><div><br></div></blockquote><div><br></div><div>Hey Rowan,</div><=
div><br></div><div>When working on nested classes, I did spend quite a b=
it of time tinkering with alternative implementations. One of those impl=
ementations was having the ability for classes to have their own class t=
ables (both literally and emulated via name mangling) which would have a=
llowed for classes to have private classes that could share names with e=
xternal classes. This turned out to be an utter disaster of an idea for =
many reasons. Namely, PHP doesn't really have any native support for sha=
dowing names. Sure, there is aliasing via use statements, but that only =
works for classes outside the current namespace. As long as we can guara=
ntee that a module acts as a special namespace (under the hood), the onl=
y potential for collisions will be in the module itself.</div><div><br><=
/div><div>All that is to say that I don't think comparing PHP to JavaScr=
ipt is appropriate when considering modules. JavaScript doesn't have typ=
es, so I can pass you an EpicStringV2 when you're expecting an EpicStrin=
gV1, and as long as my EpicStringV2 has the right prototypical behavior =
and data, it will work just fine. PHP is typed, and fairly strongly type=
d. There is effectively no way to have multiple versions of the same typ=
e running around a codebase and pass type checks. Changing this would be=
 effectively impossible and probably unsound from a type-theory perspect=
ive.</div><div><br></div><div id=3D"qt-sig121229152">=E2=80=94 Rob</div>=
</blockquote><div><br></div><div>Haha, I just reread your email and real=
ized we're basically saying the same thing (I think?).</div><div><br></d=
iv><div id=3D"sig121229152">=E2=80=94 Rob</div></body></html>
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