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Date: Sat, 7 Feb 2015 20:57:35 +0000
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References: <8703B53E-2C4A-4AC6-95C4-D4F19C6D5221@ajf.me> <CAB6YZuy-FFERAqcOjtyiizzwUZb6qrnMw8FCf8zur1wsL37Opg@mail.gmail.com> <9E1C2427-0295-4F3E-BD29-04DA84321067@ajf.me>
To: =?utf-8?Q?Pavel_Kou=C5=99il?= <pajousek@gmail.com>
Subject: Re: [PHP-DEV] [VOTE] Scalar Type Hints
From: ajf@ajf.me (Andrea Faulds)

Hi,

> On 7 Feb 2015, at 20:47, Andrea Faulds <ajf@ajf.me> wrote:
>=20
>> On 7 Feb 2015, at 10:57, Pavel Kou=C5=99il <pajousek@gmail.com> =
wrote:
>>=20
>> I just realized it now (I brought it up in a different manner when
>> there was discussion about the RFC), but I didn't notice there was a
>> totally false statement about it in the RFC itself. You probably
>> should fix it. I'm speaking about the "Strict type checking, which is
>> used by many popular programming languages, particularly ones which
>> are statically-typed, such as Java, C#, Haskell, or Facebook's Hack.
>> It is also used for non-scalar parameter type hints in PHP. With this
>> approach, an argument is only accepted if its type is exactly the =
same
>> as the parameter." paragraph.
>>=20
>> This is NOT true (at least for C# and Java), as you can read here in
>> the documentations of respecitve languages so you should not compare
>> the strict version of the typing implemented in PHP with other
>> strongly typed languages, because the PHP's "strict" is stricter than
>> strongly static typed languages. I really hope noone voted with the
>> thought that the strict typing acts as it does in Java and C#.
>>=20
>> https://msdn.microsoft.com/en-us/library/y5b434w4.aspx
>> http://docs.oracle.com/javase/specs/jls/se7/html/jls-5.html#jls-5.1.2
>=20
> I don=E2=80=99t think it=E2=80=99s unfair. There=E2=80=99s a limited =
set of permitted conversions in some strictly-typed languages, but =
it=E2=80=99s still strictly-typed.

To add to the previous email:

* Most of these conversions are between different sizes of the same type =
(float/double, char/short/int/long, etc.), but this is irrelevant to PHP =
which has only one size for each type
* The other ones are between types (int to float)
* Always allowing implicit conversions from float to int is very likely =
to cause data loss, so it=E2=80=99s not unreasonable for PHP to prevent =
this specific case
* Always allowing implicit conversions from int to float is sometimes =
going to cause data loss, so it may also be reasonable for PHP to =
prevent this specific case
* Requiring an exact type match has the least mental overhead, and =
allows types to be checked at compile-time

Thanks.

--
Andrea Faulds
http://ajf.me/