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Date: Mon, 24 Nov 2014 23:36:28 +0000
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To: Alain Williams <addw@phcomp.co.uk>
Subject: Re: [PHP-DEV] [RFC] Unicode Escape Syntax
From: ajf@ajf.me (Andrea Faulds)


> On 24 Nov 2014, at 23:29, Alain Williams <addw@phcomp.co.uk> wrote:
>=20
> There is a big difference with \u or \U and \x or \o and that is the =
number of
> characters that follow the escape. \x has 2, \o has 3 - both are short =
and easy
> to count with the eye. \U012345 is quite long and it is not so =
visually obvious
> where it should end.
>=20
> Ergo: I prefer Andrea's "\u{0123}" as it is going to be more robust =
against typos.

Typos are an angle I hadn=E2=80=99t quite considered, but yes, this =
syntax is better against that. Importantly, it=E2=80=99s a compile error =
if you produce a broken literal, while if you screwed up the brace-free =
style you=E2=80=99d probably just get a mangled string.

> One other thing that we could do is to allow code points to be named, =
with \U
> (capital 'U') eg:
>=20
> echo "\U{arabic letter alef}\n=E2=80=9D;

Ooh, that=E2=80=99s an interesting idea. I believe Perl actually has =
this already, although it uses the \N syntax:

http://perldoc.perl.org/perlreref.html#ESCAPE-SEQUENCES

Is something like that what you have in mind?

> If you think that it is a bad idea, please update the RFC to say why =
this is a
> bad idea and so why it is not going to happen - for now.
>=20
> It would be nice since a code point is just a big number without any =
really obvious
> meaning, but a name makes for greater clarity.
>=20
> However: I suspect that interpretting this might be considerably =
slower which
> means slower compilation.

I=E2=80=99ll add it to the Future Scope part.

One issue with this, however, is that we=E2=80=99d have to include a =
Unicode info database from somewhere with the names of the characters. =
That=E2=80=99d probably mean requiring ICU or something like it, which =
the current patch doesn=E2=80=99t do.
--
Andrea Faulds
http://ajf.me/