Share your favourite PHP trick!

Personally, I'm a big fan of the ?? syntax (available from PHP 7 and up).

An example:

<?php

// Long syntax
!empty($book->author->name) ? $book->author->name : 'no known author'

// Short syntax with the coalescing operator
$book->author->name ?? 'no known author'

// Chaining ?? can tidy up your views (arbitrary example here)
Hello, <?= $user->nickname ?? $user->name ?? 'stranger' ?>

Well, even though it's not really about PHP, it's still a nice trick. Let's A/B test some code!

<?php

/*/
$a = 1 + 1;
/*/
$a = 2 + 2;
/**/
echo $a . "\n";

This will print case no. 2.

If you put another asterisk (*) in the first little comment block, see what happens!

<?php

/**/
$a = 1 + 1;
/*/
$a = 2 + 2;
/**/
echo $a . "\n";

Suddenly, this will print case no. 1!

By just putting/removing one asterisk it will toggle both cases.

I bet this will work in multiple languages. However, I didn't test it anywhere but PHP.