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Date: Tue, 15 Jul 2014 20:44:55 +0100
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To: Rowan Collins <rowan.collins@gmail.com>
Subject: Re: [PHP-DEV] [RFC] Scalar Type Hinting With Casts (re-opening)
From: ajf@ajf.me (Andrea Faulds)


On 15 Jul 2014, at 19:59, Rowan Collins <rowan.collins@gmail.com> wrote:

> Or, to implement a "safe cast", and catch the error case:
>=20
> if ( false =3D=3D=3D $foo =3D filter_var($foo, FILTER_VALIDATE_INT) ) =
{
>     $foo =3D 1;
> }
>=20
> Yuck! :P

The patch and RFC introduce a new set of =93safe=94 conversion functions =
which we could use for these safe casts. In fact, it makes normal casts =
use them too now, they just ignore the errors.

PHP has pseudo-functions, maybe we could use that format? =
cast_int($foo)?

Actually, perhaps the solution is an ahead-of-time check:

    if (safe_cast($foo, int)) {
        $bar =3D (int!)$foo;
    } else {
        $bar =3D 1;
    }

Perhaps safe_int or something would be better. Anyhow, (int!) would =
error if the cast was unsafe, but as you'd checked ahead of time, it =
wouldn=92t error here.

That, or perhaps something with an optional argument:

    $bar =3D cast_int($foo, 1); // defaults to 1 if cast unsafe
    $bar =3D cast_int($foo); // unsafe cast

But I don=92t like that approach as it doesn=92t match the nice (int!) =
syntax.

This just occurred to me:

    $bar =3D (int?)$foo ? (int!)$foo : 1;

I=92m not sure if that=92s horrible or brilliant.

--
Andrea Faulds
http://ajf.me/