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Date: Tue, 14 Apr 2026 16:27:50 +0200
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Subject: Re: [PHP-DEV] [RFC] Context Managers
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From: rob@bottled.codes ("Rob Landers")

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On Tue, Apr 14, 2026, at 16:18, Rob Landers wrote:
>=20
>=20
> On Tue, Nov 4, 2025, at 21:13, Larry Garfield wrote:
>> Arnaud and I would like to present another RFC for consideration: Con=
text Managers.
>>=20
>> https://wiki.php.net/rfc/context-managers
>>=20
>> You'll probably note that is very similar to the recent proposal from=
 Tim and Seifeddine.  Both proposals grew out of casual discussion sever=
al months ago; I don't believe either team was aware that the other was =
also actively working on such a proposal, so we now have two.  C'est la =
vie. :-)
>>=20
>> Naturally, Arnaud and I feel that our approach is the better one.  In=
 particular, as Arnaud noted in an earlier reply, __destruct() is unreli=
able if timing matters.  It also does not allow differentiating between =
a success or failure exit condition, which for many use cases is absolut=
ely mandatory (as shown in the examples in the context manager RFC).
>>=20
>> The Context Manager proposal is a near direct port of Python's approa=
ch, which is generally very well thought-out.  However, there are a few =
open questions as listed in the RFC that we are seeking feedback on.
>>=20
>> Discuss. :-)
>>=20
>> --=20
>>   Larry Garfield
>>   larry@garfieldtech.com
>>=20
>=20
> Hi Larry/Arnaud,
>=20
> This is a pretty exciting thread and fascinating proposal. That being =
said, I have a couple of subtle questions that don't seem to be answered=
 in the (very long) thread or the RFC itself -- If I missed it, please l=
et me know:
>  1.  What happens if a Fiber is suspended in the using block and never=
 resumed? When is the using block released to clean up the context?
>  2. There's still no mention of how this should affect debugging, will=
 we see the "desugared" or "sugared" version? Is that even a concern for=
 the RFC?
>  3. I will say it is weird to have exitContext return an exception; bu=
t what happens if an exception is thrown during exitContext? Why not jus=
t have it return void and throw if you need to throw instead of having t=
wo paths to the same thing?
>  4. Looking at the desugared form ... I'm a bit confused: if exitConte=
xt is called during the finally path and returns an exception, it is jus=
t swallowed? But if it is thrown, it won't be?
>  5. That being said, I don't think the RFC shares with us when we shou=
ld return an exception vs. throw an exception.
>=20
> =E2=80=94 Rob

Maybe the desugared version should look more like this?

} catch (\Throwable $e) {
    try {
        $__mgr->exitContext($e);
    } catch (\Throwable $cleanupException) {
        throw new ContextManagerException(
            $cleanupException->getMessage(),
            previous: $e
        );
    }
    throw $e;
}

=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 Tue, Apr 14, 2026, at 16:18, Rob Landers wrote:</di=
v><blockquote type=3D"cite" id=3D"qt" style=3D""><div><br></div><div><br=
></div><div>On Tue, Nov 4, 2025, at 21:13, Larry Garfield wrote:</div><b=
lockquote type=3D"cite" id=3D"qt-qt" style=3D""><div>Arnaud and I would =
like to present another RFC for consideration: Context Managers.</div><d=
iv><br></div><div><a href=3D"https://wiki.php.net/rfc/context-managers">=
https://wiki.php.net/rfc/context-managers</a></div><div><br></div><div>Y=
ou'll probably note that is very similar to the recent proposal from Tim=
 and Seifeddine.&nbsp; Both proposals grew out of casual discussion seve=
ral months ago; I don't believe either team was aware that the other was=
 also actively working on such a proposal, so we now have two.&nbsp; C'e=
st la vie. :-)</div><div><br></div><div>Naturally, Arnaud and I feel tha=
t our approach is the better one.&nbsp; In particular, as Arnaud noted i=
n an earlier reply, __destruct() is unreliable if timing matters.&nbsp; =
It also does not allow differentiating between a success or failure exit=
 condition, which for many use cases is absolutely mandatory (as shown i=
n the examples in the context manager RFC).</div><div><br></div><div>The=
 Context Manager proposal is a near direct port of Python's approach, wh=
ich is generally very well thought-out.&nbsp; However, there are a few o=
pen questions as listed in the RFC that we are seeking feedback on.</div=
><div><br></div><div>Discuss. :-)</div><div><br></div><div>--&nbsp;</div=
><div>&nbsp; Larry Garfield</div><div>&nbsp;&nbsp;<a href=3D"mailto:larr=
y@garfieldtech.com">larry@garfieldtech.com</a></div><div><br></div></blo=
ckquote><div><br></div><div>Hi Larry/<span class=3D"qt-color" style=3D"c=
olor:rgb(51, 51, 51);">Arnaud,</span></div><div><br></div><div><span cla=
ss=3D"qt-color" style=3D"color:rgb(51, 51, 51);">This is a pretty exciti=
ng thread and fascinating proposal. That being said, I have a couple of =
subtle questions that don't seem to be answered in the (very long) threa=
d or the RFC itself -- If I missed it, please let me know:</span></div><=
ol><li>&nbsp;What happens if a Fiber is suspended in the using block and=
 never resumed? When is the using block released to clean up the context=
?</li><li>There's still no mention of how this should affect debugging, =
will we see the "desugared" or "sugared" version? Is that even a concern=
 for the RFC?</li><li>I will say it is weird to have exitContext return =
an exception; but what happens if an exception is thrown during exitCont=
ext? Why not just have it return void and throw if you need to throw ins=
tead of having two paths to the same thing?</li><li>Looking at the desug=
ared form ... I'm a bit confused: if exitContext is called during the fi=
nally path and returns an exception, it is just swallowed? But if it is =
thrown, it won't be?</li><li>That being said, I don't think the RFC shar=
es with us when we should return an exception vs. throw an exception.</l=
i></ol><div><br></div><div id=3D"qt-sig121229152">=E2=80=94 Rob</div></b=
lockquote><div><br></div><div>Maybe the desugared version should look mo=
re like this?</div><div><br></div><pre style=3D"border-top-width:1px;bor=
der-right-width:1px;border-bottom-width:1px;border-left-width:1px;border=
-top-style:solid;border-right-style:solid;border-bottom-style:solid;bord=
er-left-style:solid;border-top-color:rgb(204, 204, 204);border-right-col=
or:rgb(204, 204, 204);border-bottom-color:rgb(204, 204, 204);border-left=
-color:rgb(204, 204, 204);border-image-source:initial;border-image-slice=
:initial;border-image-width:initial;border-image-outset:initial;border-i=
mage-repeat:initial;border-top-left-radius:3px;border-top-right-radius:3=
px;border-bottom-right-radius:3px;border-bottom-left-radius:3px;backgrou=
nd-image:initial;background-position-x:initial;background-position-y:ini=
tial;background-size:initial;background-repeat:initial;background-attach=
ment:initial;background-origin:initial;background-clip:initial;backgroun=
d-color:rgb(246, 246, 246);font-family:menlo, consolas, monospace;font-s=
ize:90%;margin-top:7px;margin-right:0px;margin-bottom:7px;margin-left:0p=
x;padding-top:7px;padding-right:10px;padding-bottom:7px;padding-left:10p=
x;white-space-collapse:preserve;text-wrap-mode:wrap;overflow-wrap:break-=
word;">} catch (\Throwable $e) {=0A    try {=0A        $__mgr-&gt;exitCo=
ntext($e);=0A    } catch (\Throwable $cleanupException) {=0A        thro=
w new ContextManagerException(=0A            $cleanupException-&gt;getMe=
ssage(),=0A            previous: $e=0A        );=0A    }=0A    throw $e;=
=0A}</pre><div><br></div><div id=3D"sig121229152">=E2=80=94 Rob</div></b=
ody></html>
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