Coalesce function for PHP?

null-coalescing-operator, optimization, php

Solution

PHP 7 introduced a real coalesce operator:

echo $_GET['doesNotExist'] ?? 'fallback'; // prints 'fallback'

If the value before the `??` does not exists or is `null` the value after the `??` is taken.

The improvement over the mentioned `?:` operator is, that the `??` also handles undefined variables without throwing an `E_NOTICE`.

Problem

Many programming languages have a coalesce function (returns the first non-NULL value, example). PHP, sadly in 2009, does not. What would be a good way to implement one in PHP until PHP itself gets a coalesce function?

Original source

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