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In-Reply-To: <000301d02fd3$456ab390$d0401ab0$@tutteli.ch>
Date: Wed, 14 Jan 2015 08:48:19 +0000
Cc: PHP Internals List <internals@lists.php.net>
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To: Robert Stoll <php@tutteli.ch>
Subject: Re: [PHP-DEV] [RFC] Scalar Type Hints v0.2
From: ajf@ajf.me (Andrea Faulds)

Hey Robert,

> On 14 Jan 2015, at 08:22, Robert Stoll <php@tutteli.ch> wrote:
>=20
> I had a few thoughts on the new proposed =
declare(strict_typehints=3DTRUE); construct and I must say I do not =
really like that we would have different behaviour just based on a =
directive. This is quite ugly from a readability point of view since I =
as user cannot easily see whether somewhere (above) in the code the =
directive was set (I have changed my mind a little bit below - left it =
here for traceability purposes). Which brings me to the question what =
happens with the following code:
>=20
> function foo(int $a){}  //is weak right?
> declare(strict_typehinting=3DTRUE);
>=20
>=20
> I guess it is weak since you wrote: "If this boolean value is TRUE, =
strict type-checking mode is used for function calls in the remainder of =
the file"
> Maybe it is a good idea to add such an example to the examples as =
well.

Yes, it only affects stuff which comes after it. But in the example you =
just gave it doesn=E2=80=99t do anything, because the type checking mode =
is about the caller (where the function is called), not the callee =
(where the function is defined).

A better example:

<?php
foo(1.0); // weak
declare(strict_typehints=3DTRUE);
foo(1); // strict

> Now, having rethought my own email, I think we should enforce some =
code style to avoid a huge mess. Why not declare that the directive =
needs to be the very first statement inside a namespace scope (unless =
the directive block syntax is used). This way it would be easily =
verifiable for the user if strict mode is in place or not. But then =
again, we could also argue that is up to code conventions/code =
guidelines and they should specify whether mixing both modes is ok and =
where the directive has to be placed. So re-rethinking what I just wrote =
I would say it is fine as it is now but we should at least consider if =
we want to enforce some code practice to avoid a mess.

We could possible require it to be at the top of the file, maybe. Though =
I expect people will probably do this anyway. I=E2=80=99m sure it=E2=80=99=
ll become part of PSR-whatever and there=E2=80=99ll be some sort of =
standard.

By the way, you can mark some blocks as having different behaviour, =
e.g.:

<?php
declare(strict_typehints=3DTRUE) {
    foo(1);
}
declare(strict_typehints=3DFALSE) {
    bar(2);
}

This way, it=E2=80=99s more obvious that they have different behaviour.

> Now another point: "Whether or not the function being called was =
declared in a file that uses strict or weak type checking is entirely =
irrelevant. The type checking mode depends on the file where the =
function is called."
> Seems quite strange to me but fair enough, why not -- actually makes =
perfectly sense for this RFC -> leaving it to the user to decide what =
he/she likes :-)=20

That=E2=80=99s the idea. I didn=E2=80=99t like the idea of having an API =
force you to deal with a particular approach, especially since it=E2=80=99=
d mean some of your calls would be strict, others weak. This way it=E2=80=99=
s completely consistent: everything is strict, or everything is weak, =
and you get to choose. :)

Thanks for your comments.
--
Andrea Faulds
http://ajf.me/