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Date: Mon, 18 Jun 2012 00:52:54 +0200
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To: Marc Easen <marc@easen.co.uk>
Subject: Re: [PHP-DEV] Support negative indexes for arrays and strings
From: lars@strojny.net (Lars Strojny)

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Hi Marc,


Am 17.06.2012 um 21:53 schrieb Marc Easen:
[...]
> Numerical keyed array:
>=20
>    $a =3D array('foo', 'bar', 'baz');
>    $a[0] =3D=3D=3D 'foo'
>=20
> I would expect:
>=20
>    $a[-1] =3D=3D=3D 'baz';
>=20
> An string keyed array:
>=20
>    $b =3D array('foo' =3D> 1, 'bar' =3D> 2, 'baz' =3D> 3);
>    $b[0] =3D=3D=3D 1;
>=20
> Would generate an E_NOTICE:   PHP Notice:  Undefined offset: 0 in php =
shell code on line 1.
> An negative offset would also generate the same E_NOTICE.
>=20
> So going back to your point, the change would only be to numeric based =
arrays (list) and strings. It could be possible to string keyed arrays =
to be accessed by the numeric counter parts, but I'm not familiar to =
comment on if this is even possible.

I see, must have overread that. This makes it slightly better but not =
optimal, as too varying behavior for hashes vs. lists will be harder to =
explain. We could go down that road and separate the both more and more =
but given the history (and the usage patterns) of arrays in PHP I'm not =
convinced this is a good idea.

I would prefer something like this (and no, I don't propose using ':' as =
an operator for real):

$string =3D "bar";
$string:-1                   // "b"
$string:-2                   // "r"
$string:-10                   // NULL

$list =3D array("one", "two", "three");
$list:-1                     // "three"
$list:-2                     // "two"
$list:-10                    // NULL

$hash =3D array("one" =3D> 1, "two" =3D> 2, "three" =3D> 3)
$hash:-1                     // 3
$hash:-2                     // 2
$hash:-10                    // 10

As using arrays as hashes let=92s them behave in a FIFO kind of way, we =
can do proper slicing.

> It seems this topic has generated a lot of interest, I feel the best =
way to proceed would be to write a RFC. I've never written one before so =
could someone give me access to create a page on the RFC site or create =
a RFC for me and give me permission to update it, my username is =
'easen'.

For sure, RFC makes sense. I like the general idea, I=92m just not sure =
about the syntax.

cu,
Lars=

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