PHP Spread Syntax in Array Declaration

PHP supports the spread syntax for variadic functions.

In JavaScript, you can use the spread syntax to do this:

var a = [1, 2];
var b = [...a, 3, 4];
console.log(b); // [1, 2, 3, 4]

However, trying to do this in PHP:

$a = [1, 2];
$b = [...$a, 3, 4];
var_dump($b);die;

Results in this error:

Parse error: syntax error, unexpected ‘…’ (T_ELLIPSIS), expecting ‘]’

Is using the spread syntax this way not allowed in PHP? If so, is there an equally-as-elegant way to achieve the same effect?

Answer

The spread operator in the arrays RFC has been implemented in PHP 7.4:

$ary = [3, 4, 5];
return [1, 2, ...$ary]; // same as [1, 2, 3, 4, 5]

Caveat: The unpacked array/Traversable can only have integer keys. For string keys array_merge() is still required.