[RFC][Under Discussion] Add functions array_key_first() and array_key_last()

Hi Levi,

Am 20.06.2018 um 04:47 schrieb Levi Morrison:

 list($key, $value) = array_first($input);
 // $key will be null if the call failed

 list($key, $value) = array_last($input);
 // $key will be null if the call failed

Your proposed functions would be implementable with the internal
functions but I think this approach doesn't provide a clean function
interface as it forces the user to evaluate the wanted value from the
returned array structure by using either the list() construct or
something like $key = array_first($input)[0];

I believe two functions with this interface will be confusing and less
intuitive for the developer.
If I use a function I expect it to give me a return value which I can
use without any further post processing $wantedValue =
fancyFunction($someInput);

Your wish cannot be granted for array_value_last and
array_value_first; you cannot know by itself if there is a failure
condition. As proposed you have to write:

if (!empty($input)) {
    $value = array_value_last($input)
    // do something
}

This is not "clean". In contrast here is with my proposal:

if ([$key, $value] = array_last($input) {
    // do something
}

If I need the last/first key and value (which is a real use-case and
why I thought of this in the first place) then in your proposal I have
to do:

if (!empty($input)) {
    $key = array_key_last($input);
    $value = array_value_last($input);

}

Or use the key to get the value; roughly the same amount of code.
Either way is not as clean as:

if ([$key, $value] = array_last($input) {
    // do something
}

Hopefully I have shown that for various use-cases the proposed
interface is cleaner and that you cannot argue against it on those
grounds.

Adding 4 functions which cover 4 use-cases, with ugly names, and 2 of
them having poor failure semantics is not a good direction. Adding
only 2 functions which cover 6 use-cases, with nice names, and good
failure conditions is better. Please reconsider.

Brainstorm suggestions:

1. Keys being stored as reference:

$valueOutput = array_first(array $array, ?string &$keyOutput = null);

2. Function will returns value or key, by option (similar to
   array_filter()):

​​
array_first(array $array, int $options = ARRAY_VALUE);
​
​
array_first(array $array, int $options = ARRAY_KEY); ​

​3. ​
F
​unction will returns value or key, by boolean argument:

array_first(array $array, bool $returnKeyInsteadOfValue = false);
array_first(array $array, bool $returnKeyInsteadOfValue = true); ​

4. Specific method to return key instead of value:

array_first(array $array);
array_first_key(array $array);

5. Consider that keys could be obtained via array_keys(), so array_first()
   should just care about values:

array_first(array_keys($array));

Em qui, 21 de jun de 2018 às 13:18, Larry Garfield larry@garfieldtech.com
escreveu:

I don't think I'm getting all the mail I am supposed to. I hope this gets
seen.

I propose 2 functions only which I believe covers the use-cases that
all 4 of these do and more, with shorter names, and the ability to
discern whether the call succeeded or not.

list($key, $value) = array_first($input);
// $key will be null if the call failed

list($key, $value) = array_last($input);
// $key will be null if the call failed

I have tested it with user-land functions and seems to work as
intended in all success and failure conditions. Verification that it
works as intended with internal functions is necessary but this seems
a much better proposal to me.

Can I vote "heck no" to any function that does multi-return, thus making
it
impossible to chain or pass directly to another function? That's an idiom
that just doesn't make sense in PHP.

--Larry Garfield

--
David Rodrigues

Hi all,

I just want to add some information that I feel it's missing in that
discussion - I'm sorry if it was mentioned already.

1. It's already possible to extract the key and value of any index
   position of an array using array_slice: https://3v4l.org/mib99

2. "array_[key|value]first|last" is in my opinion not a good
   option as it lacks the possibility to extract key/value from any position.
   Something like "array[key|value]_index($array, $index)" where $index
   would be the index position or negative index position from right.

Thanks,
Marc

Am 21.06.2018 um 18:16 schrieb Larry Garfield:

I don't think I'm getting all the mail I am supposed to. I hope this gets
seen.

I propose 2 functions only which I believe covers the use-cases that
all 4 of these do and more, with shorter names, and the ability to
discern whether the call succeeded or not.

 list($key, $value) = array_first($input);
 // $key will be null if the call failed

 list($key, $value) = array_last($input);
 // $key will be null if the call failed

I have tested it with user-land functions and seems to work as
intended in all success and failure conditions. Verification that it
works as intended with internal functions is necessary but this seems
a much better proposal to me.

Can I vote "heck no" to any function that does multi-return, thus making it
impossible to chain or pass directly to another function? That's an idiom
that just doesn't make sense in PHP.

--Larry Garfield