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Date: Thu, 15 Aug 2024 19:40:11 +0100
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Subject: Re: [PHP-DEV] function autoloading v4 RFC
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From: imsop.php@rwec.co.uk ("Rowan Tommins [IMSoP]")

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On 15/08/2024 16:22, Rob Landers wrote:
> Hello internals,
>
> I've decided to attempt an RFC for function autoloading. After reading 
> hundreds of ancient (and recent) emails relating to the topic along 
> with several abandoned RFCs from the past, and after much review, I've 
> decided to put forth a variation of a previous RFC, as it seemed the 
> least ambitious and the most likely to work:
>
> https://wiki.php.net/rfc/function_autoloading4


Hi Rob,

While brevity can sometimes be a virtue, I feel like there's a lot left 
to the reader's interpretation here.

Specifically, one of the main issues that has come up in previous 
discussions of the topic is the behaviour of unqualified function names, 
which check the current namespace first, then fall back to global scope. 
Your RFC implies an approach to this, but doesn't actually spell it out, 
nor discuss its pros and cons.

The fully qualified case is straight-forward: the autoloader is called, 
and if still not defined, an error is thrown. But for the unqualified 
case, there are multiple scenarios, and you only give the behaviour for 
one of them:

Defined in current namespace? | Defined in global namespace? | Proposed 
behaviour
------------------------------+------------------------------+--------------------------------------
No                            | No                           | 
Autoloader called, with prefixed name
No                            | Yes                          | ???
Yes                           | No                           | ???
Yes                           | Yes                          | ???

The third and fourth cases (where the function exists in the current 
namespace) are straight-forward, although it wouldn't hurt to spell them 
out: presumably, the namespaced function is used as now, so no 
autoloading is needed.

The complex case has always been the second one: the function doesn't 
exist in the current namespace, but *does* exist in the global 
namespace. (Or, an autoloader *defines* it in the global namespace.)

In concrete terms, what does this code output:

spl_autoload_register( function($function, $type) { echo "$function..."; 
}, type:SPL_AUTOLOAD_FUNCTION);

namespace Foo {
    foreach (['hello', 'goodbye'] as $word) {
       echo strlen($word), ';';
    }
}

a) "Foo\strlen...5;Foo\strlen...7;" (the autoloader is called every time 
the function is encountered)
b) "Foo\strlen...5;7;" (the autoloader is called once, then somehow 
marked not to run again for this name
c) "5;7;" (the autoloader is never run for this code)


Note that there is an open RFC implementing option (b) by Gina and Dan 
here: https://wiki.php.net/rfc/core-autoloading Last I heard, Gina was 
still hoping to get back to it.


On a different note, there is no mention of autoloading namespaced 
constants in this RFC, unlike in some previous proposals. Is this a 
conscious decision to leave them out of scope, or an oversight?


Regards,

-- 
Rowan Tommins
[IMSoP]

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    <div class="moz-cite-prefix"><font face="monospace">On 15/08/2024
        16:22, Rob Landers wrote:<br>
      </font></div>
    <blockquote type="cite"
      cite="mid:2716f729-4008-4f75-8412-861d8960b746@app.fastmail.com">
      <meta http-equiv="content-type" content="text/html; charset=UTF-8">
      <title></title>
      <style type="text/css"><font face="monospace">p.MsoNormal,p.MsoNoSpacing{margin:0}</font></style>
      <div><font face="monospace">Hello internals,<br>
        </font></div>
      <div><font face="monospace"><br>
        </font></div>
      <div><font face="monospace">I've decided to attempt an RFC for
          function autoloading. After reading hundreds of ancient (and
          recent) emails relating to the topic along with several
          abandoned RFCs from the past, and after much review, I've
          decided to put forth a variation of a previous RFC, as it
          seemed the least ambitious and the most likely to work:<br>
        </font></div>
      <div><font face="monospace"><br>
        </font></div>
      <div><font face="monospace"><a
            href="https://wiki.php.net/rfc/function_autoloading4"
            moz-do-not-send="true" class="moz-txt-link-freetext">https://wiki.php.net/rfc/function_autoloading4</a></font></div>
    </blockquote>
    <p><font face="monospace"><br>
      </font></p>
    <p><font face="monospace">Hi Rob,</font></p>
    <p><font face="monospace">While brevity can sometimes be a virtue, I
        feel like there's a lot left to the reader's interpretation
        here.</font></p>
    <p><font face="monospace">Specifically, one of the main issues that
        has come up in previous discussions of the topic is the
        behaviour of unqualified function names, which check the current
        namespace first, then fall back to global scope. Your RFC
        implies an approach to this, but doesn't actually spell it out,
        nor discuss its pros and cons.</font></p>
    <p><font face="monospace">The fully qualified case is
        straight-forward: the autoloader is called, and if still not
        defined, an error is thrown. But for the unqualified case, there
        are multiple scenarios, and you only give the behaviour for one
        of them:</font></p>
    <p><font face="monospace">Defined in current namespace? | Defined in
        global namespace? | Proposed behaviour<br>
------------------------------+------------------------------+--------------------------------------<br>
        No                            | No                           |
        Autoloader called, with prefixed name<br>
        No                            | Yes                          |
        ???<br>
      </font><font face="monospace">Yes                           | No
                                  | ???<br>
      </font><font face="monospace">Yes                           |
        Yes                          | ???</font></p>
    <p><font face="monospace">The third and fourth cases (where the
        function exists in the current namespace) are straight-forward,
        although it wouldn't hurt to spell them out: presumably, the
        namespaced function is used as now, so no autoloading is needed.</font></p>
    <p><font face="monospace">The complex case has always been the
        second one: the function doesn't exist in the current namespace,
        but *does* exist in the global namespace. (Or, an autoloader
        *defines* it in the global namespace.)<br>
      </font></p>
    <p><font face="monospace">In concrete terms, what does this code
        output:</font></p>
    <p><font face="monospace">spl_autoload_register( function($function,
        $type) { echo "$function..."; }, type:SPL_AUTOLOAD_FUNCTION);<br>
      </font></p>
    <p><font face="monospace">namespace Foo {<br>
           foreach (['hello', 'goodbye'] as $word) {<br>
              echo strlen($word), ';';<br>
           }<br>
        }<br>
      </font></p>
    <p><font face="monospace">a) "Foo\strlen...5;Foo\strlen...7;" (the
        autoloader is called every time the function is encountered)<br>
        b) "Foo\strlen...5;7;" (the autoloader is called once, then
        somehow marked not to run again for this name<br>
        c) "5;7;" (the autoloader is never run for this code)</font></p>
    <p><font face="monospace"><br>
      </font></p>
    <p><font face="monospace">Note that there is an open RFC
        implementing option (b) by Gina and Dan here:
        <a class="moz-txt-link-freetext" href="https://wiki.php.net/rfc/core-autoloading">https://wiki.php.net/rfc/core-autoloading</a> Last I heard, Gina was
        still hoping to get back to it.<br>
      </font></p>
    <p><font face="monospace"><br>
      </font></p>
    <p><font face="monospace">On a different note, there is no mention
        of autoloading namespaced constants in this RFC, unlike in some
        previous proposals. Is this a conscious decision to leave them
        out of scope, or an oversight?</font></p>
    <p><font face="monospace"><br>
      </font></p>
    <p><font face="monospace">Regards,<br>
      </font></p>
    <pre class="moz-signature" cols="72">-- 
Rowan Tommins
[IMSoP]</pre>
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