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Date: Wed, 22 Oct 2014 16:49:07 +0400
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To: Weinand Bob <bobwei9@hotmail.com>
Cc: Andrea Faulds <ajf@ajf.me>, PHP Internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] [RFC] Safe Casting Functions
From: dmitry@zend.com (Dmitry Stogov)

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for me it's weird that to_int() that must return "int" may return not "int"=
.
NULL with ?? seems better than FALSE :)

but if we talk about safety, we should be able to relay on to_int() return
value without additional checks.

Thanks. Dmitry.

On Wed, Oct 22, 2014 at 4:35 PM, Weinand Bob <bobwei9@hotmail.com> wrote:

> So, what exactly changes here if we have a second parameter or just retur=
n
> null by default?
> It doesn=E2=80=99t make any difference, it=E2=80=99s just another way to =
write it:
>
> to_int($a, $default)
> or
> to_int($a) ?? $default
>
> Also, if you want exceptions, you always can wrap a userland function
> around it =E2=80=94 but I=E2=80=99d rather not wrap an userland function =
around something
> throwing an exception=E2=80=A6 inefficient and weird.
>
> Thanks,
> Bob
>
> > Am 22.10.2014 um 12:27 schrieb Dmitry Stogov <dmitry@zend.com>:
> >
> > "null" or "false" return value would make these functions not really
> > useful, because they won't guarantee to return desired type.
> >
> > printf("%d\n", to_int("abcd")); // will print 0
> >
> > The only reliable option to support wrong input is exceptions.
> > On the  other hand, exceptions maybe difficult to use or inefficient.
> > We may avoid exceptions throwing, if provide a default value:
> >
> > function to_int(mixed $a , int $default_value =3D null): int;
> > function to_double(mixed $a , double $default_value =3D null): double;
> > function to_string(mixed $a, string $default_value =3D null): string;
> >
> > Thanks. Dmitry.
> >
> > On Wed, Oct 22, 2014 at 12:37 PM, Bob Weinand <bobwei9@hotmail.com>
> wrote:
> >
> >> 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 t=
he
> >> to_{type}() functions cannot return a meaningful value, just return "n=
o
> >> 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>:
> >>>
> >>> Good evening,
> >>>
> >>> I am presenting a new RFC to add a set of three functions to do
> >> validated casts for scalar types:
> >>>
> >>> https://wiki.php.net/rfc/safe_cast
> >>>
> >>> Please read it.
> >>>
> >>> Thanks!
> >>> --
> >>> Andrea Faulds
> >>> http://ajf.me/
>

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