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Date: Tue, 22 Jan 2019 11:33:35 +0100
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To: PHP internals <internals@lists.php.net>
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Subject: Coalesce assign operator (??=) implemented
From: nikita.ppv@gmail.com (Nikita Popov)

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Hi internals,

Some time ago an RFC for the ??= operator has been accepted:
https://wiki.php.net/rfc/null_coalesce_equal_operator

However, due to implementation difficulties, the RFC hasn't landed since
then. I'm happy to say that these difficulties are resolved now, and ??=
has landed with
https://github.com/php/php-src/commit/a50198d0fef652ca052cda642d6e98a9101eb73f
.

To summarize the important ??= semantics: $a ??= $b is roughly equivalent
to $a ?? ($a = $b). In $a[foo()] ??= bar() the function foo() will be
evaluated exactly once, and bar() will be evaluated iff $a[foo()] is null
(or unset).

Regards,
Nikita

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