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In-Reply-To: <1b5790ec-1ffb-461e-b3fc-91d59a6db831@www.fastmail.com>
Date: Wed, 8 Dec 2021 06:26:23 +0700
Message-ID: <CAG4FTXwFREP0A7oGPJnAs2mKiykHCm55KvGWYv-OFHhQA51McA@mail.gmail.com>
To: Larry Garfield <larry@garfieldtech.com>
Cc: php internals <internals@lists.php.net>
Content-Type: text/plain; charset="UTF-8"
Subject: Re: [PHP-DEV] RFC [Discussion] array_column results grouping
From: the.liquid.metal@gmail.com (Hendra Gunawan)

>
> And if you want to map, reduce, or filter without grouping? Then you can't
> really use this function. And as noted, the order in which you apply those
> operations may matter, and no order is necessarily more obvious or beneficial

You can modify it slightly if you eager to:

    array_group(
        ...
        null|int|string|array $index_key,
        ...
    ): array

If You provide `null`, it will operate on a bare array, no grouping involved.
As a consequence, users have to provide `reducer` or `mapper`. So virtually,
You design `array_group` to swallow `array_reduce` and `array_map`. Though,
`array_map` is actually a different API compared to `array_reduce` or
`array_group`.

Interestingly, you will get a better quality of code if you include `reducer: `
and `mapper: ` consistently, whatever array level you work with.

    // `array_reduce` and `array_map` alternative
    array_group($array, null, reducer: $fnReducer);
    array_group($array, null, mapper: $fnMapper);

    array_group($array, "level1", reducer: $fnReducer);
    array_group($array, "level1", mapper: $fnMapper);
    array_group($array, ["level1", "level2"], reducer: $fnReducer);
    array_group($array, ["level1", "level2"], mapper: $fnMapper);

I hope there is no bias between the proposed name (`array_group`) and its
functionality.

>
> Either of these approaches would be superior to cramming more functionality
> into a single-purpose function to turn it into a single-function swiss army
> knife:

Not a swiss army knife, just a penknife. AS i wrote before, it is just a
shortcut. If you really mind about that, we can cancel `filter` and `sorter`,
leaving only `reducer` and `mapper`. Thought, we can filtering and sorting
before `array_group`, but i don't know whether it is as accurate as embedding
them into `array_group` or not. If not, we have to iterate manually, do
filtering and/or sorting, then reducing/mapping.

>
> https://wiki.php.net/rfc/comprehensions
> https://wiki.php.net/rfc/pipe-operator-v2

Of course these are wonderful proposals. Yes, they are superior. To be honest,
I really hope they are landed in PHP. I already imagine what part of my code
will be replaced by them. Since I am not a C coder and totally blind about the
engine, I don't have my own opinion whether we lost good things or not, by not
adding them to PHP.