Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:92311
Mailing-List: contact internals-help@lists.php.net; run by ezmlm
Received-SPF: error (pb1.pair.com: domain fleshgrinder.com from 212.232.25.163 cause and error)
Reply-To: internals@lists.php.net
References: <CAFMT4Nq+VdfYS+eKbdbmPr92-X1QYCE2eOtPGo6Zu1qgAOGkhA@mail.gmail.com>
 <CAFMT4Nq=QPN9fOMtKa7GDDkf-AECAXjN9WRtn84nUjtKK-zD7w@mail.gmail.com>
 <570E99AC.3090804@fleshgrinder.com>
 <CAFMT4Nq7JV=iv=_AKjez+B8JxZ+rucD4LkEJgHuUg15o7r2hMg@mail.gmail.com>
 <570EA5EB.8090501@fleshgrinder.com> <570EAB0D.6080706@gmail.com>
 <570EB67E.8010908@garfieldtech.com>
 <5B147E88-CC0A-4CBC-A49D-C7FE3BF557C0@zend.com>
 <6F.C3.12455.94C5F075@pb1.pair.com> <20160414094440.GF19347@phcomp.co.uk>
 <CAKSD0w6Gd7uN2L=d3VfnK-Mj+cwjpcGtCpjfD6iq+VMmJVxkhA@mail.gmail.com>
 <570FD94F.90703@fleshgrinder.com> <570FE8A9.4020809@gmail.com>
To: Stanislav Malyshev <smalyshev@gmail.com>, internals@lists.php.net
Message-ID: <570FEE98.1030401@fleshgrinder.com>
Date: Thu, 14 Apr 2016 21:25:12 +0200
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101
 Thunderbird/38.7.2
MIME-Version: 1.0
In-Reply-To: <570FE8A9.4020809@gmail.com>
Content-Type: multipart/signed; micalg=pgp-sha256;
 protocol="application/pgp-signature";
 boundary="TkdFuUQp4TxMB78l7FoCjqeIQ98N6C9Hs"
Subject: Re: [PHP-DEV] Re: Improving PHP's type system
From: php@fleshgrinder.com (Fleshgrinder)

--TkdFuUQp4TxMB78l7FoCjqeIQ98N6C9Hs
Content-Type: multipart/mixed; boundary="O4NbGNmVCnq4UJGSV4oWwwH3srqucEqmw"
From: Fleshgrinder <php@fleshgrinder.com>
Reply-To: internals@lists.php.net
To: Stanislav Malyshev <smalyshev@gmail.com>, internals@lists.php.net
Message-ID: <570FEE98.1030401@fleshgrinder.com>
Subject: Re: [PHP-DEV] Re: Improving PHP's type system
References: <CAFMT4Nq+VdfYS+eKbdbmPr92-X1QYCE2eOtPGo6Zu1qgAOGkhA@mail.gmail.com>
 <CAFMT4Nq=QPN9fOMtKa7GDDkf-AECAXjN9WRtn84nUjtKK-zD7w@mail.gmail.com>
 <570E99AC.3090804@fleshgrinder.com>
 <CAFMT4Nq7JV=iv=_AKjez+B8JxZ+rucD4LkEJgHuUg15o7r2hMg@mail.gmail.com>
 <570EA5EB.8090501@fleshgrinder.com> <570EAB0D.6080706@gmail.com>
 <570EB67E.8010908@garfieldtech.com>
 <5B147E88-CC0A-4CBC-A49D-C7FE3BF557C0@zend.com>
 <6F.C3.12455.94C5F075@pb1.pair.com> <20160414094440.GF19347@phcomp.co.uk>
 <CAKSD0w6Gd7uN2L=d3VfnK-Mj+cwjpcGtCpjfD6iq+VMmJVxkhA@mail.gmail.com>
 <570FD94F.90703@fleshgrinder.com> <570FE8A9.4020809@gmail.com>
In-Reply-To: <570FE8A9.4020809@gmail.com>

--O4NbGNmVCnq4UJGSV4oWwwH3srqucEqmw
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: quoted-printable

On 4/14/2016 8:59 PM, Stanislav Malyshev wrote:
> Hi!
>=20
>> I don't know what is complicated about "string|Stringable" or "Foo|Bar=
"
>> since it is super self-explanatory. However, I find myself checking th=
e
>=20
> It may be self-explanatory for you. It's much less self-explanatory for=

> somebody just starting to learn. It is also very dangerous - if it's
> either Foo or Bar, can you call Foo::stuff on it or not? If it's string=

> or not string, can you call strlen on it? Etc., etc. It adds a lot of
> cognitive load and complicates the whole picture. You may have a
> specific use case where it is useful (which we have yet to see btw) but=

> please remember it's a language with literally millions of use cases an=
d
> users.
>=20

Reduce assertions*, enhance self-documentation, making code more robust,
perform checks in the VM and not in userland, ...

function fn($arg) {
    assert('is_string($arg) || method_exists($arg, "__toString")');
}

interface Stringable {
    function __toString(): string;
}

function fn(string|Stringable $arg) {
    // :)
}

You can find more information on the topic here:

https://en.wikipedia.org/wiki/Tagged_union

* Assertions in PHP are very error prone if combined with refactoring
due to the fact that one should enclose the actual assertion in a string.=


--=20
Richard "Fleshgrinder" Fussenegger


--O4NbGNmVCnq4UJGSV4oWwwH3srqucEqmw--

--TkdFuUQp4TxMB78l7FoCjqeIQ98N6C9Hs
Content-Type: application/pgp-signature; name="signature.asc"
Content-Description: OpenPGP digital signature
Content-Disposition: attachment; filename="signature.asc"

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2

iQIcBAEBCAAGBQJXD+6bAAoJEOKkKcqFPVVrwlUP/0chhuQJauUM72CrKwxtereG
MrL+UZwtzT4q7JiQfg0AFE5dgOQ8AQkq7I5TBbuEKpUcf/9+jkoTiAECkNzLlvPU
aztPE4ssdcwKBq2ANeL+ziNHVprsKQ9Nq3rGNm+Nb02B1tFETGSBsLkm4u6+jCPi
9JgCCzuXM5k/6tnSWTD1l8N6StDKJfzbid0Sulhcr8sdJpKjFK1zhuzS2PNYK2Cz
3nZ3EdAXe2HJDRPgBsL/2g9z9zhNBNKKwRC92cvLiysFGo+mCNluUMOI6lryjuUt
C5tw3rn+Ai/Z1pCvusloXvgsP95HqUGnKUVv6Nn1dArMeKGOnykWdhLzHDEKn73y
7QMHY0/PZQ/MBdHK3O2pER22UsCzXQCZFjcCg8gIi8eFAisEqmufpkEUfCafI8NM
E1eUSOYWBFjcjOUFBr6l8YpwphdIt3nbtWAJTzZ3f1plopsRwCi4oGcSuvDslfi3
d6MDIaylwuL0/wUx/AxHwuo500cL41gJl2O11I2TvZuuJgQvm9DGDtecf8D4eh6I
X6EcGb6zKdqtjBdE5fTfE752gqFHYSaqQN5wo75Gv4wI8w0Gh8cllvu12TP1SCv6
xNfMf0AQ+7WYU5xMG9Jl1ttqkbU0hFmkzZSzdeBVyO4YCy7uSDNHN56+UWpxxIpG
Pt5ZPVO4RqNUW8gSzEqQ
=VDyP
-----END PGP SIGNATURE-----

--TkdFuUQp4TxMB78l7FoCjqeIQ98N6C9Hs--