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Date: Wed, 4 Feb 2015 05:51:50 +0900
Message-ID: <CAGa2bXZqUhyTM_ErfzPsQFY-ep1465Sjos-cJ=OSmX+pyQw99w@mail.gmail.com>
To: Thomas Bley <mails@thomasbley.de>
Cc: Dmitry Stogov <dmitry@zend.com>, "internals@lists.php.net" <internals@lists.php.net>
Content-Type: multipart/alternative; boundary=001a11c11a98d929b6050e353fad
Subject: Re: [PHP-DEV] What do we need strict scalar type hints for?
From: yohgaki@ohgaki.net (Yasuo Ohgaki)

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Content-Type: text/plain; charset=UTF-8

Hi all,

On Wed, Feb 4, 2015 at 5:23 AM, Thomas Bley <mails@thomasbley.de> wrote:

> function addVat($amount) {
>   validateAmount($amount);
>   return round($amount*1.19, 2);
> }
>
> function validateAmount($amount) {
>   if (!is_int($amount) && !is_float($amount)) {
>     throw new InvalidArgumentException('Argument amount must be of the
> type int|float, '.gettype($amount).' given');
>   }
> }
>

I use such code where runtime check is required.

I prefer following for better performance/readability. i.e. Pre/Post
conditions are inside of function definition.
If PHP supports native DbC, runtime checks are omitted and script runs
faster. NOTE: Dev time checks are
done in in/out block with proper DbC design. Runtime check should be in
function body.

function addVat($amount)
in {
  // precondition check
  assert(!is_int($amount) && !is_float($amount));
  // OR
  if (!is_int($amount) && !is_float($amount)) {
    throw new InvalidArgumentException('Argument amount must be of the type
int|float, '.gettype($amount).' given');
  }
}
out {
  // postcondition check
  assert(is_numeric($__return_vlaue) && $__return_value > 0 &&
$__return_value < MAX_AMOUNT);
}
{
  // function body
  return round($amount*1.19, 2);
}

Type hints are useful for simple runtime check.
Much less lines to write ;) It also encourage users to validate their app
inputs. This is important benefits for secure apps.

Things like these encourage proper DbC design naturally. Therefore, I'm +1
for all of these.

Regards,

--
Yasuo Ohgaki
yohgaki@ohgaki.net

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