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Subject: Re: [PHP-DEV] [RFC] Scope functions
Date: Thu, 7 May 2026 00:26:33 +0200
In-Reply-To: <0187D382-80FD-432C-B0D5-B0F9D8783419@hotmail.com>
Cc: PHP internals list <internals@lists.php.net>
To: Bob Weinand <bobwei9@hotmail.com>
References: <0187D382-80FD-432C-B0D5-B0F9D8783419@hotmail.com>
From: claude.pache@gmail.com (Claude Pache)


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> Le 6 mai 2026 =C3=A0 22:09, Bob Weinand <bobwei9@hotmail.com> a =C3=A9cr=
it :
>=20
> Volker and I drafted a RFC:=20
>=20
> https://wiki.php.net/rfc/scope-functions
>=20
> Please consider it and share your feedback.
>=20
> I hope it will alleviate pain around some of the most common forms of =
Closure usage which is "execute this now as part of the called =
function", which currently can require a lot of "use ($variables)".
>=20
> For me the primary use case of use ($capturing) was always "I need =
this function later and want to explicitly document what escapes my =
function". This, however, required this straightforward usage of =
Closures to also document every single usage of a variable. Which is =
really not that beneficial at all.
>=20
> Thus the scope functions as proposed will be able to fill that gap in =
future.=20
>=20
> Thank you,
> Bob


Hi,

This is nice. As I understand it, this RFC could resolve problems that =
the Context Managers RFC tries to resolve in a simpler and more flexible =
way. (And it resolves other problems too, of course.)=20

Taking the first example from the Context Manager RFC:

```php
using (file_for_write('file.txt') =3D> $fp) {
    foreach ($someThing as $value) {
        fwrite($fp, serialize($value));
    }
}

// implementable as:

function file_for_write(string $filename): ContextManager {

    return new class($filename) implements ContextManager {

        function __construct(private readonly string $filename) { }

        private $fp;
       =20
       function enterContext() {
            $this->fp =3D @fopen($this->filename, 'w');
            if (!$this->fp) {
                throw new \RuntimeException('Couldn=E2=80=99t open =
file');
            }
            return $this->fp;
        }

        function exitContext(?\Throwable $e =3D null): ?\Throwable {
            @fclose($this->fp);
            return $e;
        }
    };
}
```

This can be rewritten as:

```php
file_for_write('file.txt', fn($fp) {
    foreach ($someThing as $value) {
        fwrite($fp, serialize($value));
    }
});


// implementable as (which is simpler: one function instead of a whole =
class):

function file_for_write (string $filename, callable $do_write): void {
    $fp =3D @fopen($filename, 'w');
    if (!$fp) {
        throw new \RuntimeException('Couldn=E2=80=99t open file');
    }
    try {
        $do_write($fp);
    } finally {
        @fclose($fp);
    }
}
```

For those of us that abhor exceptions in case of recoverable failure, =
there is even more. With this RFC, one can easily return true/false (or =
whatever other signal) for success/failure, while Context Manager =
strongly leans towards the use of exceptions (although, of course, it =
remains possible to assign the outcome to a variable and to exit the =
context with `break` or `goto`):

```php
$ok =3D file_for_write('file.txt', fn($fp) {
    foreach ($someThing as $value) {
	if (something_is_wrong_with($value))
            return false;
        fwrite($fp, serialize($value));
    }
    return true;
});

// implementable as (which is more flexible: exceptions are not the only =
type of signal):

#[\NoDiscard]
function file_for_write (string $filename, callable $do_write): bool {
    $fp =3D @fopen($filename 'w');
    if (!$fp) {
        return false;
    }
    try {
        return $do_write($fp);
    } finally {
        @fclose($fp);
    }
}
```


=E2=80=94Claude




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<html aria-label=3D"message body"><head><meta http-equiv=3D"content-type" =
content=3D"text/html; charset=3Dutf-8"></head><body =
style=3D"overflow-wrap: break-word; -webkit-nbsp-mode: space; =
line-break: after-white-space;"><br =
id=3D"lineBreakAtBeginningOfMessage"><div><br><blockquote =
type=3D"cite"><div>Le 6 mai 2026 =C3=A0 22:09, Bob Weinand =
&lt;bobwei9@hotmail.com&gt; a =C3=A9crit :</div><br =
class=3D"Apple-interchange-newline"><div>

<meta http-equiv=3D"Content-Type" content=3D"text/html; =
charset=3Dus-ascii">

<div style=3D"overflow-wrap: break-word; -webkit-nbsp-mode: space; =
line-break: after-white-space;">
<div>Volker and I drafted a RFC:&nbsp;</div>
<div><br>
</div>
<a =
href=3D"https://wiki.php.net/rfc/scope-functions">https://wiki.php.net/rfc=
/scope-functions</a>
<div></div>
<div><br>
</div>
<div>Please consider it and share your feedback.</div>
<div><br>
</div>
<div>I hope it will alleviate pain around some of the most common forms =
of Closure usage which is "execute this now as part of the called =
function", which currently can require a lot of "use =
($variables)".</div>
<div><br>
</div>
<div>For me the primary use case of use ($capturing) was always "I need =
this function later and want to explicitly document what escapes my =
function". This, however, required this straightforward usage of =
Closures to also document every single usage of a variable.
 Which is really not that beneficial at all.</div>
<div><br>
</div>
<div>Thus the scope functions as proposed will be able to fill that gap =
in future.&nbsp;</div>
<div><br>
</div>
<div>Thank you,</div>
<div>Bob</div>
</div>

=
</div></blockquote></div><br><div><br></div><div>Hi,</div><div><br></div><=
div>This is nice. As I understand it, this RFC could resolve problems =
that the Context Managers RFC tries to resolve in a simpler and more =
flexible way. (And it resolves other problems too, of =
course.)&nbsp;</div><div><br></div><div>Taking the first example from =
the Context Manager =
RFC:</div><div><br></div><div>```php</div><div><div>using =
(file_for_write('file.txt') =3D&gt; $fp) {</div><div>&nbsp; &nbsp; =
foreach ($someThing as $value) {</div><div>&nbsp; &nbsp; &nbsp; &nbsp; =
fwrite($fp, serialize($value));</div><div>&nbsp; &nbsp; =
}</div><div>}</div></div><div><br></div><div>// implementable =
as:</div><div><div><br></div><div>function file_for_write(string =
$filename): ContextManager {</div><div><br></div><div>&nbsp; &nbsp; =
return new class($filename) implements ContextManager =
{</div><div><br></div><div>&nbsp; &nbsp; &nbsp; &nbsp; function =
__construct(private readonly string $filename) { =
}</div><div><br></div><div>&nbsp; &nbsp; &nbsp; &nbsp; private =
$fp;</div><div>&nbsp; &nbsp; &nbsp; &nbsp;&nbsp;</div><div>&nbsp; &nbsp; =
&nbsp; &nbsp;function enterContext() {</div><div>&nbsp; &nbsp; &nbsp; =
&nbsp; &nbsp; &nbsp; $this-&gt;fp =3D @fopen($this-&gt;filename, =
'w');</div><div>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; if =
(!$this-&gt;fp) {</div><div>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; =
&nbsp; &nbsp; throw new \RuntimeException('Couldn=E2=80=99t open =
file');</div><div>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; =
}</div><div>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; return =
$this-&gt;fp;</div><div>&nbsp; &nbsp; &nbsp; &nbsp; =
}</div><div><br></div><div>&nbsp; &nbsp; &nbsp; &nbsp; function =
exitContext(?\Throwable $e =3D null): ?\Throwable {</div><div>&nbsp; =
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; =
@fclose($this-&gt;fp);</div><div>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; =
&nbsp; return $e;</div><div>&nbsp; &nbsp; &nbsp; &nbsp; =
}</div><div>&nbsp; &nbsp; =
};</div><div>}</div></div><div>```</div><div><br></div><div>This can be =
rewritten =
as:</div><div><br></div><div>```php</div><div><div>file_for_write('file.tx=
t', fn($fp) {</div><div>&nbsp; &nbsp; foreach ($someThing as $value) =
{</div><div>&nbsp; &nbsp; &nbsp; &nbsp; fwrite($fp, =
serialize($value));</div><div>&nbsp; &nbsp; =
}</div><div>});</div><div><br></div><div><br></div><div>// implementable =
as (which is simpler: one function instead of a whole =
class):</div><div><br></div><div>function file_for_write (string =
$filename, callable $do_write): void {</div><div>&nbsp; &nbsp; $fp =3D =
@fopen($filename, 'w');</div><div>&nbsp; &nbsp; if (!$fp) =
{</div><div>&nbsp; &nbsp; &nbsp; &nbsp; throw new =
\RuntimeException('Couldn=E2=80=99t open file');</div><div>&nbsp; &nbsp; =
}</div><div>&nbsp; &nbsp; try {</div><div>&nbsp; &nbsp; &nbsp; &nbsp; =
$do_write($fp);</div><div>&nbsp; &nbsp; } finally {</div><div>&nbsp; =
&nbsp; &nbsp; &nbsp; @fclose($fp);</div><div>&nbsp; &nbsp; =
}</div><div>}</div></div><div>```</div><div><br></div><div>For those of =
us that abhor exceptions in case of recoverable failure, there is even =
more. With this RFC, one can easily return true/false (or whatever other =
signal) for success/failure, while Context Manager strongly leans =
towards the use of exceptions (although, of course, it remains possible =
to assign the outcome to a variable and to exit the context with `break` =
or `goto`):</div><div><br></div><div><div>```php</div><div><div>$ok =3D =
file_for_write('file.txt', fn($fp) {</div><div>&nbsp; &nbsp; foreach =
($someThing as $value) {</div><div><span class=3D"Apple-tab-span" =
style=3D"white-space:pre">	</span>if =
(something_is_wrong_with($value))</div><div>&nbsp; &nbsp; &nbsp; &nbsp; =
&nbsp; &nbsp; return false;</div><div>&nbsp; &nbsp; &nbsp; &nbsp; =
fwrite($fp, serialize($value));</div><div>&nbsp; &nbsp; =
}</div><div>&nbsp; &nbsp; return =
true;</div><div>});</div></div></div><div><br></div><div>// =
implementable as (which is more flexible: exceptions are not the only =
type of =
signal):</div><div><br></div><div>#[\NoDiscard]</div><div><div><div>functi=
on file_for_write (string $filename, callable $do_write): bool =
{</div><div>&nbsp; &nbsp; $fp =3D @fopen($filename =
'w');</div><div>&nbsp; &nbsp; if (!$fp) {</div><div>&nbsp; &nbsp; &nbsp; =
&nbsp; return false;</div><div>&nbsp; &nbsp; }</div><div>&nbsp; &nbsp; =
try {</div><div>&nbsp; &nbsp; &nbsp; &nbsp; return =
$do_write($fp);</div><div>&nbsp; &nbsp; } finally {</div><div>&nbsp; =
&nbsp; &nbsp; &nbsp; @fclose($fp);</div><div>&nbsp; &nbsp; =
}</div><div>}</div></div><div>```</div></div><div><br></div><div><br></div=
><div>=E2=80=94Claude</div><div><br></div><div><br></div><div><br></div></=
body></html>=

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