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Date: Wed, 22 Oct 2014 10:37:11 +0200
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References: <66B7B28C-2651-4A71-AC2A-55D4C7BB3DDC@ajf.me>
To: Andrea Faulds <ajf@ajf.me>
Subject: Re: [PHP-DEV] [RFC] Safe Casting Functions
From: bobwei9@hotmail.com (Bob Weinand)

I know we have that already discussed a lot now, but I=E2=80=99d like to =
expose my points on the return value here:

I imagine code like (supposing that we ever will have scalar typehints):

function acceptsInt (int $i =3D null) {
    if ($i =3D=3D=3D null) {
        $i =3D 2 /* default value */;
    }
    /* do something with $i */
}

When we return false:
acceptInt(($tmp =3D to_int($_GET["userinput"])) =3D=3D=3D false ? null : =
$tmp);

When we throw an exception:
try {
    acceptInt(to_int($_GET["userinput"]));
} catch (CastingException $e) {
    acceptInt(null);
}

When we just return null:
acceptInt(to_int($_GET["userinput"]));

Also, when we want to pass a default value defined outside of the =
function, it=E2=80=99s a lot easier now with the coalesce operator:
acceptInt(to_int($_GET["userinput=E2=80=9C]) ?? 2 /* default value */);


Also, independently of possible scalar typehints:

Generally exceptions are also a bad idea as the casts probably will be =
used on external input and exceptions are **not** a way to handle =
malformed user input. Really not.
Furthermore, false is a bad idea in the same sense (if we get scalar =
type hints once), because people then might just catch the =
EngineException=E2=80=A6

Also, null means "no value"; that=E2=80=99s exactly what we need. If the =
to_{type}() functions cannot return a meaningful value, just return "no =
value", that means null. And not false, which is a real value.

That=E2=80=99s why I strongly feel that null is the only true thing to =
return here.

Thanks,
Bob

> Am 21.10.2014 um 00:57 schrieb Andrea Faulds <ajf@ajf.me>:
>=20
> Good evening,
>=20
> I am presenting a new RFC to add a set of three functions to do =
validated casts for scalar types:
>=20
> https://wiki.php.net/rfc/safe_cast
>=20
> Please read it.
>=20
> Thanks!
> --
> Andrea Faulds
> http://ajf.me/