Notable updates in PHP version >= 7

As of this writing the latest PHP version is 7.4, I will update this post when i found notable updates in PHP v7.x releases.

Return type declarations ​

The same types are available for return type declarations as are available for argument type declarations.

function arraysSum(array ...$arrays): array
{
    return array_map(function(array $array): int {
        return array_sum($array);
    }, $arrays);
}

Nullable return types are also allowed by prefixing the type name with a question mark.

Null coalescing operator ​

$username = isset($_GET['user']) ? $_GET['user'] : 'nobody';

// is equivalent to ...
$username = $_GET['user'] ?? 'nobody';

// can also be more ...
$username = $_GET['user'] ?? $_POST['user'] ?? 'nobody';

Spaceship operator ​

The code below returns -1, 0 or 1 when $a is respectively less than, equal to, or greater than $b

echo $a <=> $b;

Anonymous classes ​

You can now create a class without a name, perfect for closure type as the example below.

$app = new Application;
$app->setLogger(new class implements Logger {
    public function log(string $msg) {
        echo $msg;
    }
});

Symmetric array destructuring ​

The shorthand array syntax ([]) may now be used to destructure arrays for assignments (including within foreach), as an alternative to the existing list() syntax, which is still supported.

$data = ['Juan', '28'],

// list() style
list($name, $age) = $data;

// [] style
[$name, $age] = $data;

For array with non-integer or non-sequential keys, you can specify keys in list() or []

$keysData = ["age" => 1, "name" => 'Juan'];

// list() style
list("id" => $age, "name" => $name) = $keysData;

// [] style
["id" => $age, "name" => $name] = $keysData;

Multi catch exception handling ​

Multiple exceptions per catch block may now be specified using the pipe character |. This is useful for when different exceptions from different class hierarchies are handled the same.

<?php
try {
    // some code
} catch (FirstException | SecondException $e) {
    // handle first and second exceptions
}

Typed properties ​

Class properties now support type declarations.

<?php
class User {
    public int $id;
    public string $name;
}

Arrow functions ​

Arrow functions provide a shorthand syntax for defining functions with implicit by-value scope binding.

$y = 1;
$func1 = fn($x) => $x + $y;

// equivalent to using $y by value:
$func2 = function ($x) use ($y) {
    return $x + $y;
};

Null coalescing assignment operator ​

Assign a value when not yet set, empty or undefined.

<?php
$array['key'] ??= $someValue;

// is roughly equivalent to
if (!isset($array['key'])) {
    $array['key'] = $someValue;
}

Unpacking inside arrays ​

Basically unpacking array inside another array. Example below explains it very clear.

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