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In-Reply-To: <003f01d0405e$5d1bf080$1753d180$@tutteli.ch>
Date: Wed, 4 Feb 2015 18:12:14 +0000
Cc: Dmitry Stogov <dmitry@zend.com>,
 Sebastian Bergmann <sebastian@php.net>,
 PHP Internals <internals@lists.php.net>
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To: Robert Stoll <php@tutteli.ch>
Subject: Re: [PHP-DEV] What do we need strict scalar type hints for?
From: ajf@ajf.me (Andrea Faulds)

Hi Robert,

> On 4 Feb 2015, at 09:38, Robert Stoll <php@tutteli.ch> wrote:
>=20
> Personally I am not in favour of the declare approach because the user =
will need to switch between strict context and non-strict context which =
will be quite challenging, anti-efficient (in terms of productivity) and =
most probably another source for bugs.

I=E2=80=99ve found this not to be quite true in practice. When I ported =
my app to use strict scalar hints, very little broke - and this is an =
app that took advantage of weak typing everywhere. I realise switching =
contexts might be a little painful, but it doesn=E2=80=99t seem to be as =
bad as I expected. It looks to me like much PHP code is already fairly =
strict and consistent with its types.

I think it=E2=80=99s mostly just edge cases where things break with =
strict types on. Any strict code will work fine as =E2=80=9Cweak=E2=80=9D =
code, and most weak code will work fine as strict code, I think.

> Yet, I have to defend Andrea's RFC here since the claims made that it =
will break all kind of existing code is just not true (or I got the RFC =
completely wrong).
>=20
> sin(1) would only be broken if and only if the user has decided to use =
it in a strict mode. Consider the following:
>=20
> User A writes the file index.php
>=20
> <?php
> $a =3D sin(1); //perfectly fine
> include 'test_strict.php'
> ?>
>=20
> and user B writes test_strict.php
>=20
> <?php
> declare(strict=3D1);
> $b =3D sin(1); //will fail and that's ok [*] since the user decided to =
be in strict mode
> ?>
>=20
> As far as I can tell user A which want to code in non-strict mode =
could do so also in the future - no error is reported, no problem at =
all. Only user B would get the error and only because he/she wanted to =
be informed when his/her code is not strict.
>=20
> [*] we could actually distinguish between int literals/constants and =
int variables. The above case would be fine as well since 1 can be int =
or float (pretty much as Haskell is handling it)

Yeah, I only had int/float issues when I turned on strict mode in my =
app. And that caught a bug, actually, so I was quite thankful for it.

--
Andrea Faulds
http://ajf.me/