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In-Reply-To: <alpine.DEB.2.11.1407281459350.3793@whisky.home.derickrethans.nl>
Date: Mon, 28 Jul 2014 15:19:25 +0100
Cc: Nikita Popov <nikita.ppv@gmail.com>,
 Julien Pauli <jpauli@php.net>,
 PHP Internals <internals@lists.php.net>
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References: <CAMUwpuRJVmWwAMMdzAeoec=tvgkW1L++jxhDKjKbWvQNh5C7JQ@mail.gmail.com> <CAF+90c_HUkUQes2vt9x07+d7JMpt99DtEo9b9pRD_YQj6vF6TA@mail.gmail.com> <FCDF6A43-3935-4F1D-AC31-41BE47F4BAD2@ajf.me> <alpine.DEB.2.11.1407281459350.3793@whisky.home.derickrethans.nl>
To: Derick Rethans <derick@php.net>
Subject: Re: [PHP-DEV] Thoughts on C version supported for PHP-Next
From: ajf@ajf.me (Andrea Faulds)


On 28 Jul 2014, at 15:00, Derick Rethans <derick@php.net> wrote:

>> Well, we don=92t need to allow all of C99. We can simply allow using=20=

>> features that are widely supported and actually useful. For example,=20=

>> declarations between statements,
>=20
> I think that makes code a lot less readable, so I would not be in =
favour=20
> allowing this in our coding guidelines.

Really? I=92ve found that declaring everything in advance makes for =
hard-to-read code. To take an example from code I=92ve written =
(admittedly not C code - GML if anyone=92s curious - but it might as =
well be), the first line of a function looked like this:

    var list, hashList, text, i, pluginname, pluginhash, realhash, url, =
handle, filesize, progress, tempfile, tempdir, failed, lastContact, =
isCached, env;

Even broken onto multiple lines, declaring everything at once isn=92t =
nice. For large functions (and some functions have to be large =
necessarily), declaring everything at the start just means a long list =
of variables and I would argue impairs code readability.

You should declare variables when and where you need them. If everything =
is done at the top, you have to scroll up to check the type of a =
variable. It also means that now-unused variables are less obvious as =
the declarations are far away from the usage, so you probably won=92t =
spot that it=92s useless unless you look at your compiler warnings.

Actually, a similar issue popped up in the code where that example was =
from. The language it was written in had some unfortunate properties, =
one of which was that variables not explicitly declared would instead be =
treated as properties of the current object. Because all the variables =
were declared at the start of the function, it was easy to miss the fact =
that some variables being used had not actually been declared. Of course =
this specific issue doesn=92t exist in C, but it is an example of why =
having to declare all your variables at the start of a function isn=92t =
really a good thing.

If nothing else, I think we should use C99=92s ability to declare =
variables between statements. It makes it more likely mistakes will be =
spotted, eases reading code, and as far as I am aware, is widely =
supported.

--
Andrea Faulds
http://ajf.me/