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Message-ID: <f5d6d324-9070-e33f-b4c2-a44029a6ef82@gmail.com>
Date: Thu, 12 Sep 2019 21:45:43 +0100
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Subject: Re: [PHP-DEV] [RFC] Reclassifying engine warnings
From: rowan.collins@gmail.com (Rowan Tommins)

On 12/09/2019 15:43, Robert Korulczyk wrote:
> One additional line will make your code much more obvious and easier to read and understand:
>
> $i ??= 0;
> $i++;


I don't find this code at all obvious:

foreach ( $something as $foo ) {
     $i ??= 0;
     $i++;
}

I mean, huh? What's that zero doing there, is it resetting the variable 
every loop?

Now, in that simple case, you can and probably should initialise the 
counter before the loop:

$i=0;
foreach ( $something as $foo ) {
     $i++;
}


But that's not the example I gave earlier! The example I gave earlier 
was a multi-dimensional array:

$foo = [];
foreach ( $something as $key1 ) {
     foreach ( $somethingElse as $key2 ) {
           $foo[$key1][$key2]++;
     }
}

Even using ??= the initialise-everything-before-use version looks like this:

$foo = [];
foreach ( $something as $key1 ) {
     foreach ( $somethingElse as $key2 ) {
           $foo[$key1] ??= [];
           $foo[$key1][$key2] ??= 0;
           $foo[$key1][$key2]++;
     }
}


Again, the values are confusing: the end result will never contain an 
empty array at the first level, and will never contain a 0 at the second 
level.

Those two lines aren't aiding the readability of that algorithm in any 
way; I have to read past them to find the actual business of the loop, 
which is counting something, using the ++ operator.

What's more, they're not preventing any bugs either! If I accidentally 
reuse $foo from a previous loop, the extra lines won't reinitialise 
anything for me; if I initialise it to empty, the two loops are 
functionally identical.


So that's where I came up with two suggestions to actually add to the 
language, rather than just taking away:

- a more granular way to express that this code is not actually 
error-prone, combining the 3 lines back into one
- or, a way to express the intent of the code more clearly, such as 
declaring the shape of an array


Regards,

-- 
Rowan Tommins (né Collins)
[IMSoP]