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References: <CANTuiHvOSimVNPpDxVE5KE8AW63HZmC5=kuSy_uRy_nJRgS9+w@mail.gmail.com>
In-Reply-To: <CANTuiHvOSimVNPpDxVE5KE8AW63HZmC5=kuSy_uRy_nJRgS9+w@mail.gmail.com>
Date: Thu, 31 Jul 2025 14:33:49 +0200
Message-ID: <CAOWwgpkvakVG6Wxn9z8X5tQAPb+0r1d6LYamEVyXhj+PjzteuQ@mail.gmail.com>
Subject: Re: [PHP-DEV] [DISCUSSION] User-land Throwable
To: Dmitry Derepko <xepozzd@gmail.com>
Cc: PHP internals <internals@lists.php.net>
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From: nicolas.grekas+php@gmail.com (Nicolas Grekas)

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> Hello PHP Internals,
>
> I would like to propose a discussion regarding two current limitations in
> PHP's exception handling system that I believe could be addressed to
> improve flexibility and developer experience.
>
> A few years ago I found that a library printed error traces wrong.
> After a little research I found that there was a mix of 3rd party
> integration error + raised error around the current bridge implementation
> (http client).
>
> There were several PHP applications with microservices architecture which
> I had access to (docker + sources).
>
> So having the message and traces I'd like to have an error chain as it can
> be done chaining several errors through a new Exception(previous: $e).
> But PHP does not allow you to manually implement Throwable. Instead you
> should extend Exception. But after that you still cannot override the
> getTrace() method because it's final.
>
> So my proposal is pretty simple: Remove both restrictions.
>
> 1. Allow user classes to implement Throwable interface directly
>
> User classes cannot implement the Throwable interface now.
>
> ```php
> class MyCustomThrowable implements Throwable {}
>
> // Fatal error: Class MyCustomThrowable cannot implement interface
> Throwable, extend Exception or Error instead
> ```
>
>
> 2. Make getTrace() non-final or provide alternative customization mechanism
>

The trace is stored in a private property, so you can use reflection to
change it.

new \ReflectionProperty(\Exception::class, 'trace')->setValue($e, $trace)

Nicolas

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<div dir=3D"ltr"><div dir=3D"ltr"></div><div class=3D"gmail_quote gmail_quo=
te_container"><blockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px=
 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir=3D=
"ltr"><div>Hello PHP Internals,<br><br>I would like to propose a discussion=
 regarding two current limitations in PHP&#39;s exception handling system t=
hat I believe could be addressed to improve flexibility and developer exper=
ience.<br><br>A few years ago I found that a library printed error traces w=
rong.<br>After a little research I found that there was a mix of 3rd party =
integration error + raised error around the current bridge implementation (=
http client).<br><br>There were several PHP applications with microservices=
 architecture which I had access to (docker + sources).<br><br>So having th=
e message and traces I&#39;d like to have an error chain as it can be done =
chaining several errors through a new Exception(previous: $e).<br>But PHP d=
oes not allow you to manually implement Throwable. Instead you should exten=
d Exception. But after that you still cannot override the getTrace() method=
 because it&#39;s final.<br><br>So my proposal is pretty simple: Remove bot=
h restrictions.<br><br>1. Allow user classes to implement Throwable interfa=
ce directly<br><br>User classes cannot implement the Throwable interface no=
w.<br><br>```php<br>class MyCustomThrowable implements Throwable {}<br><br>=
// Fatal error: Class MyCustomThrowable cannot implement interface Throwabl=
e, extend Exception or Error instead<br>```<br><br><br>2. Make getTrace() n=
on-final or provide alternative customization mechanism</div></div></blockq=
uote><div><br></div><div>The trace is stored in a private property, so you =
can use reflection to change it.</div><div><br></div><div>new \ReflectionPr=
operty(\Exception::class, &#39;trace&#39;)-&gt;setValue($e, $trace)</div><d=
iv><br></div><div>Nicolas=C2=A0</div></div></div>

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