Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:62076
Mailing-List: contact internals-help@lists.php.net; run by ezmlm
Received-SPF: pass (pb1.pair.com: domain gmail.com designates 209.85.216.170 as permitted sender)
MIME-Version: 1.0
In-Reply-To: <CAFMT4NrYKQaARXy7b2RRGWk3qredGjPOChCGMnpEg=47iuVRmw@mail.gmail.com>
References: <CAH-PCH7874id459NTuMqL6pzL=feRtaWUAiPiSqPDa73tnFy9w@mail.gmail.com>
	<501F46BE.4040407@sugarcrm.com>
	<CAFMT4NqUVF-Q_TZ_toe_7NCgYBU3J02eVWp46wf=CYRyouWdNg@mail.gmail.com>
	<50200FBD.2010506@sugarcrm.com>
	<CAFMT4NrYKQaARXy7b2RRGWk3qredGjPOChCGMnpEg=47iuVRmw@mail.gmail.com>
Date: Mon, 6 Aug 2012 21:16:19 -0400
Message-ID: <CAAyV7nEMsx5GbX4Rww=1JoO94AGt2J+9G629y7Wmm5G9+V8yUA@mail.gmail.com>
To: Levi Morrison <morrison.levi@gmail.com>
Cc: Stas Malyshev <smalyshev@sugarcrm.com>, Ferenc Kovacs <tyra3l@gmail.com>, 
	PHP Internals <internals@lists.php.net>
Content-Type: multipart/alternative; boundary=20cf3074b8fee9710a04c6a2bd13
Subject: Re: [PHP-DEV] Error handling brainstorming
From: ircmaxell@gmail.com (Anthony Ferrara)

--20cf3074b8fee9710a04c6a2bd13
Content-Type: text/plain; charset=ISO-8859-1

Levi et al:

On Mon, Aug 6, 2012 at 8:55 PM, Levi Morrison <morrison.levi@gmail.com>wrote:

> >> Because checking that the returned variable is `!== FALSE` is *way*
> >> better than throwing an exception, right?
> >
> > Yes, it is. You can control it, unlike the exception which you can not,
> > unless, again, you wrap everything into try/catch on every kind of
> > exception possible.
> >
> >> This type of thing is one of the main reasons I like PDO more than
> >> MySQLi.  In MySQLi I'm constantly checking return values.  In PDO I
> >> just wrap it all up one try/catch.  It's not like if my query fails
> >> I'm going to try a different one.  Most of the time it's just logging
> >> that something went wrong and reporting it upstream somehow.
> >
> > You are using exceptions for normal flow control. It is not what
> > exceptions should be used for. They are called exceptions for a reason.
> >
>
>
> It *should* be an exceptional situation if my database queries don't
> work properly.  I've tested my code locally, on a staging environment
> and sometimes even ran tests on the live server.  It is absolutely
> 100% an exception if something goes wrong, my friend.
>
> Opening a file? I have to agree that it should not throw an exception.
>  I was replying more to explain the benefit of exceptions than to
> refute that one possible use-case.


It should absolutely throw an exception. If you're opening a file, and the
file doesn't exist (in read mode), that's definitely an exceptional
circumstance. If it's not, you should be checking for existence first (via
file_exists() or is_readable(), etc)...

The only situations I consider non-exceptional in terms of PHP errors are
those that don't alter the flow via error return. So if fopen errors, you
can't just fread the return value. You *need* to change your execution flow
based on that error. Therefore, it is exceptional.

However, cases where you can logically continue on would not be
exceptional. Cases such as substr($string, 100) on a 2 character string,
currently raise a warning, but getting an empty string back from it allows
you to continue on. The rest of your code won't be effected by the error in
a significant way (since the case where the string is 2 characters is the
same as if it's 100 characters).

So, as a gross overgeneralization,

Can I continue on without **having** to check the return value?

Yes: Not an exceptional circumstance
No: An exceptional circumstance

Again, as a gross overgeneralization. Not as a hard rule, but as a quick
check...

Anthony

--20cf3074b8fee9710a04c6a2bd13--