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Subject: Re: [PHP-DEV] Should there be a `get_declared_enums()` function ?
To: Mike Schinkel <mike@newclarity.net>
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Date: Sat, 17 Aug 2024 07:36:26 +0200
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From: php-internals_nospam@adviesenzo.nl (Juliette Reinders Folmer)

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Hi Mike,

>
>> There is one problem I can see with this approach though: since PHP 7.4, the return value of `get_declared_classes()` (and friends) does not guarantee any particular order anymore [2].
>> So, an `array_slice($symbols, $n)` may not get you the _latest_ classes loaded, so I think this would only work if the order of classes is guaranteed in some way.
> That is a super relevant insight and one I was actually not aware of.
>
> Do you happen to know if it was triggered by an explicit RFC to that effect, or if it resulted because of a side-effect of some other implementation change?
I honestly don't know, but if I look through the PHP 7.4 RFC list, I 
have a niggling suspicion it may have something to do with the 
Preloading RFC [1] ? I may very well be wrong though.

>  From my perspective, that is definitely a BC break and one that I am surprised I never noticed before?  Do you also know if it is a case of "not guaranteed, but in-fact actual fact it always works that way, or not?"

Well, for the autoloader I previously linked to [2], it was a 
problematic change which we did have to work around, see [3] and [4] for 
details of the issues we saw (parent class vs child class order 
reversals, issues when multiple classes were declared in one file).

I haven't deep-dived into the order change, other than to validate the 
reported issues and proposed fixes.

> What if instead PHP were to implement an optional 2nd callback parameter to `include()` / `require()` / `include_once()` / `require_once()` to allow us to capture the symbols loaded and their paths? The callback function could return `void` and accept an array of `$symbols` with the following guaranteed minimum structure?
>
> $symbols = array(
>     'classes' => [],
>     'interfaces' => [],
>     'traits' => [],
>     'enums' => [],
> );

Except `include()` and friends aren't function calls, but language 
constructs/expressions and don't take parameters as such, so I don't see 
how that would be possible without changing `include()` and friends to 
function calls (along the lines of what happened for `exit` in PHP 8.4 
with non-parenthesized use still possible to mitigate the otherwise huge 
breaking change), or alternatively, introducing wrapper functions for 
the language constructs - so no change to the existing functionality, 
but new functions with a signature along the lines of 
`include_and_get_symbols( $path ): array` with the return value being 
the symbols loaded from $path.

> This approach would be a less disruptive than my prior suggestion

Not so sure about that considering the above ;-)
> What do you think if this alternate approach?

This probably needs some more bike shedding ;-)

Smile,
Juliette


1: https://wiki.php.net/rfc/preload
2: 
https://github.com/PHPCSStandards/PHP_CodeSniffer/blob/6fbbc1078094d905f0773421f13830744a144d1e/autoload.php#L153-L247
3: https://github.com/squizlabs/PHP_CodeSniffer/pull/3130
4: https://github.com/squizlabs/PHP_CodeSniffer/issues/3145

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    Hi Mike,<br>
    <br>
    <blockquote
      cite="mid:DF2F5FC7-0F5F-4000-95CF-1FBC6CDA7745@newclarity.net"
      type="cite"><br>
      <blockquote type="cite">
        <pre wrap="">There is one problem I can see with this approach though: since PHP 7.4, the return value of `get_declared_classes()` (and friends) does not guarantee any particular order anymore [2].
So, an `array_slice($symbols, $n)` may not get you the _latest_ classes loaded, so I think this would only work if the order of classes is guaranteed in some way.
</pre>
      </blockquote>
      <pre wrap="">
That is a super relevant insight and one I was actually not aware of.

Do you happen to know if it was triggered by an explicit RFC to that effect, or if it resulted because of a side-effect of some other implementation change?</pre>
    </blockquote>
    I honestly don't know, but if I look through the PHP 7.4 RFC list, I
    have a niggling suspicion it may have something to do with the
    Preloading RFC [1] ? I may very well be wrong though.<br>
    <br>
    <blockquote
      cite="mid:DF2F5FC7-0F5F-4000-95CF-1FBC6CDA7745@newclarity.net"
      type="cite">
      <pre wrap="">From my perspective, that is definitely a BC break and one that I am surprised I never noticed before?  Do you also know if it is a case of "not guaranteed, but in-fact actual fact it always works that way, or not?"</pre>
    </blockquote>
    <br>
    Well, for the autoloader I previously linked to [2], it was a
    problematic change which we did have to work around, see [3] and [4]
    for details of the issues we saw (parent class vs child class order
    reversals, issues when multiple classes were declared in one file).<br>
    <br>
    I haven't deep-dived into the order change, other than to validate
    the reported issues and proposed fixes.<br>
    <br>
    <blockquote
      cite="mid:DF2F5FC7-0F5F-4000-95CF-1FBC6CDA7745@newclarity.net"
      type="cite">
      <pre wrap="">What if instead PHP were to implement an optional 2nd callback parameter to `include()` / `require()` / `include_once()` / `require_once()` to allow us to capture the symbols loaded and their paths? The callback function could return `void` and accept an array of `$symbols` with the following guaranteed minimum structure?

$symbols = array(
   'classes' =&gt; [],
   'interfaces' =&gt; [],
   'traits' =&gt; [],
   'enums' =&gt; [],
);
</pre>
    </blockquote>
    <br>
    Except `include()` and friends aren't function calls, but language
    constructs/expressions and don't take parameters as such, so I don't
    see how that would be possible without changing `include()` and
    friends to function calls (along the lines of what happened for
    `exit` in PHP 8.4 with non-parenthesized use still possible to
    mitigate the otherwise huge breaking change), or alternatively,
    introducing wrapper functions for the language constructs - so no
    change to the existing functionality, but new functions with a
    signature along the lines of `include_and_get_symbols( $path ):
    array` with the return value being the symbols loaded from $path.<br>
    <br>
    <blockquote
      cite="mid:DF2F5FC7-0F5F-4000-95CF-1FBC6CDA7745@newclarity.net"
      type="cite">
      <pre wrap="">This approach would be a less disruptive than my prior suggestion
</pre>
    </blockquote>
    <br>
    Not so sure about that considering the above ;-)<br>
    <blockquote
      cite="mid:DF2F5FC7-0F5F-4000-95CF-1FBC6CDA7745@newclarity.net"
      type="cite">
      <pre wrap="">What do you think if this alternate approach?
</pre>
    </blockquote>
    <br>
    This probably needs some more bike shedding ;-)<br>
    <br>
    Smile,<br>
    Juliette<br>
    <br>
    <br>
    1: <a class="moz-txt-link-freetext" href="https://wiki.php.net/rfc/preload">https://wiki.php.net/rfc/preload</a><br>
    2: <span class="moz-txt-link-freetext"><a class="moz-txt-link-freetext" href="https://github.com/PHPCSStandards/PHP_CodeSniffer/blob/6fbbc1078094d905f0773421f13830744a144d1e/autoload.php#L153-L247">https://github.com/PHPCSStandards/PHP_CodeSniffer/blob/6fbbc1078094d905f0773421f13830744a144d1e/autoload.php#L153-L247</a><br>
      3: <a class="moz-txt-link-freetext" href="https://github.com/squizlabs/PHP_CodeSniffer/pull/3130">https://github.com/squizlabs/PHP_CodeSniffer/pull/3130</a><br>
      4: <a class="moz-txt-link-freetext" href="https://github.com/squizlabs/PHP_CodeSniffer/issues/3145">https://github.com/squizlabs/PHP_CodeSniffer/issues/3145</a><br>
    </span>
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