Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:117041
Message-ID: <51cf7bdf-450d-657d-cb1e-d52c3c4563f9@gmail.com>
Date: Tue, 15 Feb 2022 14:07:36 +0000
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101
 Thunderbird/91.6.0
Content-Language: en-GB
To: internals@lists.php.net
References: <A4A387E9-1D77-466D-83AA-89B78BA40814@gestixi.com>
 <67207814-3052-b116-e856-33e8440049d3@gmx.net>
In-Reply-To: <67207814-3052-b116-e856-33e8440049d3@gmx.net>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 8bit
Subject: Re: [PHP-DEV] Setting to disable the "Undefined array index" warning
From: rowan.collins@gmail.com (Rowan Tommins)

On 15/02/2022 12:54, Andreas Leathley wrote:
> The problem with your way of writing code is that it is ambiguous in
> meaning, which is why this is a warning.


I think that's a good way of looking at it. There's actually quite a lot 
of code hiding a check like "if ($array['key'])"; roughly speaking, it's 
short-hand for:

if ( array_key_exists('key', $array) && $array['key'] !== null && 
$array['key'] !== false && $array['key'] !== 0 && $array['key'] !== 0.0 
&& $array['key'] !== '' && $array['key'] !== [] )

Now, if that's what you intended, there's a syntax that's slightly more 
explicit while still being reasonably short: the empty() pseudo-function:

if ( ! empty($array['key']) )

On the other hand, if what you actually meant was this:

if ( array_key_exists('key', $array) && $array['key'] !== null )

Then you might have some bugs lurking, and actually want the isset() 
pseudo-function instead:

if ( isset($array['key']) )

For other cases, you do have to spend a few more characters to be 
explicit, often using the "??" operator; for instance, if you expect 
$array['key'] to be either unset or a boolean, and want this:

if ( array_key_exists('key', $array) && $array['key'] === true )

Then the shortest is probably something like this:

if ( $array['key'] ?? false === true )


Regards,

-- 
Rowan Tommins
[IMSoP]