Splat Operator in PHP

...$str is called a splat operator in PHP (other languages, including Ruby.)

This feature allows you to capture a variable number of arguments to a function, combined with "normal" arguments passed in if you like. It's easiest to see with an example:

<?php

function concatenate($transform, ...$strings) {
  $string = '';
  foreach($strings as $piece) {
    $string .= $piece;
  }
  return($transform($string));
}

echo concatenate("strtoupper", "I'm ", 20 + 2, " years", " old.");

Output

I'M 22 YEARS OLD.

Latest feature

After PHP 5.5.x, arrays and traversable objects can be unpacked into argument lists when calling functions by using the ... operator.

<?php
function add($a, $b, $c) {
    return $a + $b + $c;
}

$operators = [2, 3];
echo add(1, ...$operators);
?>

Output

6

That's cool. 😎