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References: <9ecce8c9-c8bc-93e3-25f0-386c2c41ca1a@gmail.com>
In-Reply-To: <9ecce8c9-c8bc-93e3-25f0-386c2c41ca1a@gmail.com>
Date: Wed, 30 Mar 2022 16:32:39 +0200
Message-ID: <CAC5V6ghWoAnqdp=vEuFAg-Wyg_Ydn5pAmVYDXqwsci+Xe9NnLw@mail.gmail.com>
To: Rowan Tommins <rowan.collins@gmail.com>
Cc: PHP Internals <internals@lists.php.net>
Content-Type: multipart/alternative; boundary="00000000000085901f05db706bfb"
Subject: Re: [PHP-DEV] Undefined variables and the array append operator
From: guilliam.xavier@gmail.com (Guilliam Xavier)

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Content-Type: text/plain; charset="UTF-8"

Hi Rowan,

Not really a "compelling reason why we should keep this inconsistency", but
I have occasionally relied on array autovivification *for sub-dimensions*,
e.g.:

```
function f(iterable $xs) {
    $map = []; // initialization!
    foreach ($xs as $x) {
        // $map[foo($x)] ??= []; not needed
        $map[foo($x)][] = bar($x); // autovivification
    }

    // Then e.g.:
    foreach ($map as $foo => $bars) {
        foreach ($bars as $bar) {
            /* ... */
        }
    }
}
```

(adapted from my https://externals.io/message/114595#114611 message in the
"Disable autovivification on false" thread).

On the other hand, I agree that `$undefined[] = $x` looks like a bug... are
both cases the exact same opcode? (if yes, I wouldn't really mind updating
my code, especially for consistency with other "append" operators like .=
or +=, and that could even be an opportunity to rewrite it in a more
"functional" style...)

Regards,

-- 
Guilliam Xavier

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