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Date: Sun, 5 Jul 2015 22:51:57 +0200
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To: Stanislav Malyshev <smalyshev@gmail.com>
Cc: =?UTF-8?Q?Johannes_Schl=C3=BCter?= <johannes@schlueters.de>, 
	PHP internals <internals@lists.php.net>
Content-Type: multipart/alternative; boundary=001a1134ce04c654a1051a26f575
Subject: Re: [PHP-DEV] Allow exceptions in __toString()
From: nikita.ppv@gmail.com (Nikita Popov)

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On Sun, Jul 5, 2015 at 10:33 PM, Stanislav Malyshev <smalyshev@gmail.com>
wrote:

> Hi!
>
> >>> I can see your concern here -- however this is nothing specific to
> >>> exceptions thrown from __toString(). There is are a number of ways you
> >>> can end up in this situation, the two most common being:
> >>
> >> I summarize this a bit freely as "We already have places which are hard
> >> to understand an predict, so let's add more!"
> >>
> >
> > That, or "Let's not be hypocrites".
>
> I don't think the position of "let's not add more unpredictable behavior
> to the engine" is adequately described as "hypocrite". We know there are
> interruption problems and such in the engine, we know some of them are
> hard to fix. However, adding a different class of those doesn't make it
> better in any way. If we find a solution that allows us to not introduce
> new unpredictable behaviors - I'm all for it, it's great. Maybe the code
> that allows to throw exceptions the same way we do with errors, maybe
> some way to not get unpredictable results on conversions. But we can't
> just ignore it because there are other problems in the engine too.


Sorry, I just find it somewhat weird that we consider some of the
exceptions generated as the result of __toString calls to be okay (error
handler exceptions), while others are considered to be too dangerous to
allow (direct exceptions).

But maybe I just approached this from the wrong direction. Instead of
allowing exceptions in __toString in combination with some hardening of the
VM, maybe we should just convert the recoverable fatal errors __toString
currently throws to actual fatal errors? Not a huge fan of doing that, but
at least it's consistent.

Nikita

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