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Date: Fri, 31 Aug 2012 09:14:10 -0400
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Subject: Re: [PHP-DEV] Support negative indexes for arrays and strings
From: rasmus@mindplay.dk (Rasmus Schultz)

Having thought about this for a while, I think this is a bad idea - here's why:

    $array = array(1001, 1002, 1003, 1004);

    $number = $array[-1]; // => 1004

    $number[-1] = 1005;

    $number = $array[-1]; // => ????

Obviously, the last statement must return 1005, since otherwise that
value would be inaccessible.

On the other hand, to know whether you have to know whether your array
is currently a hash or not - since array index now works completely
differently depending on whether your array is currently a hash or an
array.

This is not something you can currently even test for - and not
something you should really need to know or care about in the first
place. Having to know this information in certain cases would defeat
the purpose of having a single collection-type in the first place: it
really *should* work the same, all the time.

Just my $0.02...


--

From: Marc Easen <marc@easen.co.uk>
To: "internals@lists.php.net" <internals@lists.php.net>, Lars Strojny
<lars@strojny.net>
Cc:
Date: Sun, 17 Jun 2012 20:53:38 +0100
Subject: Re: [PHP-DEV] Support negative indexes for arrays and strings
Hi Lars,

I don't think there needs to be a new operator, as it is possible to
achieve this behaviour without adding a new language construct. The
odd thing with PHP as I'm sure you are aware of is that arrays can be
either a lists or a dictionary. This is where this becomes quite
difficult to implement:

Numerical keyed array:

    $a = array('foo', 'bar', 'baz');
    $a[0] === 'foo'

I would expect:

    $a[-1] === 'baz';

An string keyed array:

    $b = array('foo' => 1, 'bar' => 2, 'baz' => 3);
    $b[0] === 1;

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.

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.


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'.

Thanks,
Marc