PHP 7.4 new syntax: array extension operator

PHP 7.4 new syntax: array extension operator

The RFC vote for Spread Operator support in array expressions is that the vast majority of people agree to add this feature to PHP 7.4.

The expansion operator support parameter unpacking first existed in PHP 5.6, and this RFC expanded the use of arrays; the expansion can support Traversable arrays and objects. This is a basic example of RFC:

$parts = ['apple', 'pear'];
$fruits = ['banana', 'orange', ...$parts, 'watermelon'];
//['banana', 'orange', 'apple', 'pear', 'watermelon'];


Here is a further example:

$arr1 = [1, 2, 3];
$arr2 = [...$arr1];//[1, 2, 3]
$arr3 = [0, ...$arr1];//[0, 1, 2, 3]
$arr4 = array(...$arr1, ...$arr2, 111);//[1, 2, 3, 1, 2, 3, 111]
$arr5 = [...$arr1, ...$arr1];//[1, 2, 3, 1, 2, 3]

function getArr() {
  return ['a', 'b'];
$arr6 = [...getArr(), 'c'];//['a', 'b', 'c']

$arr7 = [ ArrayIterator(['a', 'b', 'c'])];//['a', 'b', 'c']

function arrGen() {
    for($i = 11; $i < 15; $i++) {
        yield $i;
$arr8 = [...arrGen()];//[11, 12, 13, 14]


String keys are not supported; you can only use indexed arrays. The author of the RFC explained the key support as follows:

To make the behavior consistent with argument unpacking , string keys are not supported. After encountering a string key, a recoverable error will be thrown.

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