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Date: Tue, 15 Feb 2022 15:50:48 +0000
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Subject: Re: [PHP-DEV] Setting to disable the "Undefined array index" warning
From: rowan.collins@gmail.com (Rowan Tommins)

On 15/02/2022 15:12, Guilliam Xavier wrote:
> On Tue, Feb 15, 2022 at 3:07 PM Rowan Tommins <rowan.collins@gmail.com>
> wrote:
>
>> if ( array_key_exists('key', $array) && $array['key'] !== null &&
>> $array['key'] !== false && $array['key'] !== 0 && $array['key'] !== 0.0
>> && $array['key'] !== '' && $array['key'] !== [] )
>>
> Agreed, but you forgot the most "annoying":
>
> && $array['key'] !== '0'


Ah yes, that one really demonstrates the dangers of type juggling in 
general. If it _wasn't_ considered empty, that would be inconsistent 
with how integer juggling works, but it definitely catches people out!


> Mind operator precedence! This is interpreted as:
>
> if ( $array['key'] ?? (false === true) )
>
> (obviously not intended), so you need explicit parentheses:
>
> if ( ($array['key'] ?? false) === true )


Oops, I admit I didn't test that. That does make the operator somewhat 
less attractive, and maybe it would be more straight-forward to just be 
explicit:

if ( isset($array['key']) && $array['key'] === true )


> I will also note that the "shorthands" (!empty(), isset(), ?? null) will
> also "hide" another warning when the $array variable itself is undefined


Ah, yes, so they do; as does the ?? operator, for that matter.

I seem to remember someone proposing an explicit operator for "this 
array dimension might not exist", something like this:

if ( $array[?'key'] === true )

Which would translate to:

if ( (array_key_exists('key', $array) ? $array['key'] : null) === true )


Regards,

-- 
Rowan Tommins
[IMSoP]