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Date: Mon, 2 Feb 2015 16:35:29 +0000
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To: Nikita Popov <nikita.ppv@gmail.com>
Subject: Re: [PHP-DEV] [VOTE] Combined Comparison (Spaceship) Operator
From: ajf@ajf.me (Andrea Faulds)

Hey Nikita,

> On 2 Feb 2015, at 16:32, Nikita Popov <nikita.ppv@gmail.com> wrote:
>=20
> On Mon, Feb 2, 2015 at 4:27 PM, Andrea Faulds <ajf@ajf.me> wrote:
> Hey Nikita,
>=20
> > On 2 Feb 2015, at 13:49, Nikita Popov <nikita.ppv@gmail.com> wrote:
> >
> > I've voted -1 because I think this should be a function and not an =
operator. compare($a, $b) is more obvious than $a <=3D> $b and it's not =
like writing comparison functions is such a super common use case that =
it needs the extra brevity of an operator. A function can furthermore be =
used as a callback, while an operator requires a wrapping closure.
>=20
> There=E2=80=99s no actual use for the bare comparison operation as a =
callback, though: usort($foo, =E2=80=98compare=E2=80=99); would just be =
a slow version of sort($foo);
>=20
> It may not be applicable to a direct sort() call, but it's useful for =
higher level APIs. With a function you can create APIs of the form =
`function foo(..., $comparator =3D 'compare') { ... }`, which will =
default to the "standard" comparison function without having to =
specially handle it all over the place.

Yes, that=E2=80=99s true.

I=E2=80=99d previously suggested adding a function to get a closure of =
an operator. But actually, perhaps we should just follow PHP=E2=80=99s =
traditional string typing of callables, and make =E2=80=98+=E2=80=99, =
=E2=80=98-=E2=80=98, =E2=80=98<=E2=80=98, =E2=80=98<=3D>=E2=80=99 etc. =
be valid callables?

Thus:

    function doesThing($a, $b, callable $callback =3D =E2=80=98+=E2=80=99)=
 {
        return $callback($a, $b);
    }
    doesThing(1, 2); // 3

Thoughts?

(I realise this is slightly OT.)

--
Andrea Faulds
http://ajf.me/