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Date: Thu, 12 Feb 2015 12:45:07 +0000
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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 Pavel,

> On 12 Feb 2015, at 12:39, Pavel Kou=C5=99il <pajousek@gmail.com> =
wrote:
>=20
> I don't see any problem with combination of optional parameters with
> method overloading. C# has it and it is pretty useful and works there
> without any bigger issues. Sure, the dynamic typing may be a (small)
> issue, but again, C# does it in an IMHO meaningful way as well and it
> can be used as an inspiration, should this way be chosen.

C# also doesn=E2=80=99t have dynamic typing. Plus, adding overloading to =
an existing language is more difficult.

> Overloading on scalar types - unpredictable how? Even with weak calls,
> the best candidate could be chosen?

Still likely to cause chaos. If you can overload based on scalar types, =
then foobar($a / 2) could call any of *three* different functions.

> Of course, sometimes there will be
> an abmbiguous call, but as long as there would be a way to define
> which call you want, it shouldn't be a problem as well?

=E2=80=9CA way to define which call you want=E2=80=9D? Sounds like a =
hacky workaround to me.

> Poor API - for useland code or in PHP's functions itself? But I don't
> think this should be considered as a real problem, because in userland
> code, developers are able to create a poor API even with the current
> versions of PHP.

That doesn=E2=80=99t mean we should make it any easier.

> If someone wants to shoot himself in the foot, he
> will do it in one way or another. And at the same time, polymorphism
> via method overloading can lead to a cleaner APIs, if it's used well.

I don=E2=80=99t see how. The main things it enables are optional =
parameters (which we already support) and polymorphism (which we already =
support). So you=E2=80=99d have to explain what overloading brings to =
the table beyond those two things.

> Well, about "number" type hint. How this would work, in combination
> with strict types?
>=20
> function bar(float $f) {
>    return $f * 1.23;
> }
>=20
> function foo(number $x) {
>    return bar($x);
> }
>=20
> foo(1);
>=20
> =46rom my understanding, it wouldn=E2=80=99t?

It would accept an integer or a float, because both subclass number:

    function foobar(): number {
        return 1.0; // okay
        return 1; // okay
    }

    function foo(number $x) {}
    foo(1.0); // okay
    foo(1); // okay

I don=E2=80=99t see why it =E2=80=9Cwouldn=E2=80=99t work=E2=80=9D.
--
Andrea Faulds
http://ajf.me/