PHP 7 features

Published on Jul 3, 2022

PHP 7.0

Scalar type declarations

<?php
// Coercive mode
function sumOfInts(int ...$ints)
{
    return array_sum($ints);
}

var_dump(sumOfInts(2, '3', 4.1));

int(9)

Return type declarations

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

print_r(arraysSum([1,2,3], [4,5,6], [7,8,9]));

Array
(
    [0] => 6
    [1] => 15
    [2] => 24
)

Null coalescing operator
The null coalescing operator (??) has been added as syntactic sugar for the common case of needing to use a ternary in conjunction with isset(). It returns its first operand if it exists and is not null; otherwise it returns its second operand.

<?php
// Fetches the value of $_GET['user'] and returns 'nobody'
// if it does not exist.
$username = $_GET['user'] ?? 'nobody';
// This is equivalent to:
$username = isset($_GET['user']) ? $_GET['user'] : 'nobody';

// Coalescing can be chained: this will return the first
// defined value out of $_GET['user'], $_POST['user'], and
// 'nobody'.
$username = $_GET['user'] ?? $_POST['user'] ?? 'nobody';
?>

Spaceship operator
The spaceship operator is used for comparing two expressions. It returns -1, 0 or 1 when $a is respectively less than, equal to, or greater than $b. Comparisons are performed according to PHP's usual type comparison rules.

<?php
// Integers
echo 1 <=> 1; // 0
echo 1 <=> 2; // -1
echo 2 <=> 1; // 1

// Floats
echo 1.5 <=> 1.5; // 0
echo 1.5 <=> 2.5; // -1
echo 2.5 <=> 1.5; // 1
 
// Strings
echo "a" <=> "a"; // 0
echo "a" <=> "b"; // -1
echo "b" <=> "a"; // 1
?>

Constant arrays using define()
Array constants can now be defined with define(). In PHP 5.6, they could only be defined with const.

<?php
define('ANIMALS', [
    'dog',
    'cat',
    'bird'
]);

echo ANIMALS[1]; // outputs "cat"
?>

Anonymous classes
Support for anonymous classes has been added via new class. These can be used in place of full class definitions for throwaway objects:

<?php
interface Logger {
    public function log(string $msg);
}

class Application {
    private $logger;

    public function getLogger(): Logger {
         return $this->logger;
    }

    public function setLogger(Logger $logger) {
         $this->logger = $logger;
    }
}

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

var_dump($app->getLogger());
?>

object(class@anonymous)#2 (0) {
}

Closure::call()
Closure::call() is a more performant, shorthand way of temporarily binding an object scope to a closure and invoking it.

<?php
class A {private $x = 1;}

// Pre PHP 7 code
$getX = function() {return $this->x;};
$getXCB = $getX->bindTo(new A, 'A'); // intermediate closure
echo $getXCB();

// PHP 7+ code
$getX = function() {return $this->x;};
echo $getX->call(new A);

1
1

UNICODE changes
Unicode codepoint escape syntax and IntlChar added.

Group use declarations

<?php
// Pre PHP 7 code
use some\namespace\ClassA;
use some\namespace\ClassB;
use some\namespace\ClassC as C;

use function some\namespace\fn_a;
use function some\namespace\fn_b;
use function some\namespace\fn_c;

use const some\namespace\ConstA;
use const some\namespace\ConstB;
use const some\namespace\ConstC;

// PHP 7+ code
use some\namespace\{ClassA, ClassB, ClassC as C};
use function some\namespace\{fn_a, fn_b, fn_c};
use const some\namespace\{ConstA, ConstB, ConstC};
?>

PHP 7.1

Nullable Types

function hello(): ?string
{
	return 'Hello';
}

Iterable and Void Returns

function perform_a_job() : void {
    return;
    // This is fine, it returns null
}

function perform_a_task() : void {
    // This is also fine, it returns null
}

function perform_another_task() : void {
    return true;
    // This will return an error since it is not void
}


function fonc01(iterable $data) {
    foreach ($data as $key => $val) {
        //....
    }
}

fonc01(new SplFixedArray(5));
// Works kist fine, SplFixedArray implements Iterator
// See http://php.net/manual/en/class.splfixedarray.php

Multi-Catch Exception Handling

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

PHP 8.0.0

Named arguments

htmlspecialchars($string, double_encode: false);

Attributes

class PostsController
{
    #[Route("/api/posts/{id}", methods: ["GET"])]
    public function get($id) { /* ... */ }
}

Constructor property promotion

class Point {
  public function __construct(
    public float $x = 0.0,
    public float $y = 0.0,
    public float $z = 0.0,
  ) {}
}

Union types

class Number {
  public function __construct(
    private int|float $number
  ) {}
}

new Number('NaN'); // TypeError

Match expression
Instead of old switch-case.

echo match (8.0) {
  '8.0' => "Oh no!",
  8.0 => "This is what I expected",
};
//> This is what I expected

Nullsafe operator

$country = $session?->user?->getAddress()?->country;

Saner string to number comparisons

//old way
0 == 'foobar' // true

//new way
0 == 'foobar' // false

Consistent type errors for internal functions

strlen([]); // TypeError: strlen(): Argument #1 ($str) must be of type string, array given

array_chunk([], -1); // ValueError: array_chunk(): Argument #2 ($length) must be greater than 0

PHP 8.1.0

Enumerations

enum Status
{
    case Draft;
    case Published;
    case Archived;
}
function acceptStatus(Status $status) {...}

Readonly Properties

class BlogData
{
    public readonly Status $status;
   
    public function __construct(Status $status) 
    {
        $this->status = $status;
    }
}

Source: https://www.php.net/manual/en/migration70.new-features.php#migration70.new-features.scalar-type-declarations
https://www.infoq.com/articles/php7-new-type-features/
https://www.php.net/releases/7_0_0.php
https://www.php.net/releases/8.0/en.php
https://www.php.net/releases/8.1/en.php
https://www.php.net/releases/8.2/en.php