On Fri, Jul 13, 2018 at 4:50 PM Levi Morrison <le...@php.net> wrote:
>
> On Fri, Jul 13, 2018 at 4:48 PM Levi Morrison <le...@php.net> wrote:
> >
> > On Mon, Jul 9, 2018 at 5:17 AM Woortmann, Enno <enno.woortm...@web.de>
> > wrote:
> > >
> > > Hi,
> > >
> > > as the discussion got no new contributions I'd like to start the voting
> > > for the RFC fo add new functions for the handling of outer array elements.
> > >
> > > https://wiki.php.net/rfc/array_key_first_last
> > >
> > > To have a better separation I split up the vote for the functions. The
> > > first vote covers the functions to handle keys: array_key_first() and
> > > array_key_last(). The second vote covers the corresponding functions to
> > > handle the values: array_value_first() and array_value_last().
> > >
> > > As this RFC adds functions but doesn't change the language syntax a 50%
> > > + 1 majority is required for both votes. The votes are open until
> > > 2018-07-16.
> > >
> > > The discussion for this RFC is located at
> > >
> > > https://externals.io/message/102245
> > >
> > > Regards,
> > >
> > > Enno
> > >
> > >
> > >
> > >
> > > --
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> >
> > This entire time I felt like this should be possible in pure PHP.
> > Surely, somewhere, we have this capability already? I searched quite a
> > few functions but didn't find anything.
> >
> > However, the feeling was right. Just moments ago Paul Crovella from
> > Stack Overflow mentioned to me that `array_slice` uses the terminology
> > `offset` to refer to the order of the entry rather than its key, so I
> > went looking. As far as I can tell from the [array_slice
> > implementation][1] it will not trigger copies and will be efficient if
> > using -1 to retrieve the last index. We can provide the parameter
> > `preserve_keys` an argument of true to get both the key and the value.
> > These functions *are* efficiently implementable in user-land!
> >
> > Below is a proof-of-concept for the `array_offset` function [mentioned
> > by Nicolas Grekas][2] (which by the way, neither the RFC author nor
> > anyone else responded to this suggestion) that is simply a convenience
> > wrapper over `array_slice`:
> >
> > function array_offset(array $input, int $offset): ?array {
> > $slice = array_slice($input, $offset, 1, true);
> > return count($slice) ? $slice : null;
> > }
> >
> > $assoc = ['one' => 1, 'two' => 2, 'three' => 3];
> > $packd = range(1, 4);
> >
> > var_dump(array_offset($assoc, -1));
> > var_dump(array_offset($packd, -1));
> >
> > var_dump(array_offset($assoc, 0));
> > var_dump(array_offset($packd, 0));
> >
> > Of course, the `array_slice` function can be used to build all of the
> > functions described in the RFC, as well.
> >
> > My new opinion is that no new functions are required and that
> > improving the `array_slice` documentation is all that is necessary. It
> > currently does not show any examples of it working on associated
> > arrays, which is probably why none of us (many of us experts) realized
> > this through this discussion. This is especially true as "offset" in
> > some other situations really means "key", as in
> > `ArrayAccess::offsetGet`.
> >
> > [1]:
> > https://github.com/php/php-src/blob/b9963969fd088dca6852483fdb1c6b7e1080764d/ext/standard/array.c#L3477-L3577
> > [2]: https://externals.io/message/102245#102322
>
> Small correction: Nicolas used the name `array_index`, not `array_offset`.
Unfortunately I was too hasty: `array_slice` will iterate over the
entire input range:
https://github.com/php/php-src/blob/b9963969fd088dca6852483fdb1c6b7e1080764d/ext/standard/array.c#L3538-L3552
We could add an case for when `array_slice` uses `-1`. I wonder how
common this already is. Does anyone have a tool that easily can search
open source code for usages of functions? I am interested in this
regardless of the outcome of this RFC. The documentation for
`array_slice` should also be updated independently of this RFC as
well.
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