PHP: New Features

PHP 7+: New Features.md

PHP 7.0

All features.

• Scalar type declarations: function f(int ...$args) (bool, int, float and string, in addition to array, callable, self, parent and interface/class name).
• Return type declarations: function f(): bool.
• Constant arrays using define(): define('MY_CONSTANT', [ ... ]).
• Integer division with intdiv(): var_dump(intdiv(8, 3)); // int(3).
• Spaceship operator: $a <=> $b → {-1, 0, 1} (less, equal, bigger).
• Null coalescing operator:

  // $username = isset($_GET['user']) && !is_null($_GET['user']) ? $_GET['user'] : 'nobody';
  $username = $_GET['user'] ?? 'nobody';
  
  $username = $_GET['user'] ?? $_POST['user'] ?? 'nobody';

• Group use declarations: use some\namespace\{ClassA, ClassB, ClassC as C}.
• Generator return expressions.
• Generator delegation.
• Anonymous classes.

PHP 7.1

All features.

• iterable pseudo-type: function f(iterable $i) (accepts arrays and Traversable's).
• Nullable types: function f(?string $arg): ?int.
• Void functions: function f(): void.
• Multi catch exception handling:

  try {
      ...
  } catch (Exception1 | Exception2 $e) { ... }

• Class constant visibility:

  class MyClass
  {
      const           PUBLIC_CONSTANT_1 = 1;
      public const    PUBLIC_CONSTANT_2 = 2;
      protected const PROTECTED_CONSTANT = 4;
      private const   PRIVATE_CONSTANT = 8;
  }

• Symmetric array destructuring:

  $data = [
      [1, 'Tom'],
      [2, 'Fred'],
  ];
  
  ...
  
  [$id, $name] = $data[0]; // list($id, $name) = $data[0];
  
  foreach ($data as [$id, $name]) { // foreach ($data as list($id, $name))
      ...
  }

• Support for keys in list():

  $data = [
      ['id' => 1, 'name' => 'Tom'],
      ['id' => 2, 'name' => 'Fred'],
  ];
  
  list('id' => $id, 'name' => $name) = $data[0];
  
  foreach ($data as list('id' => $id, 'name' => $name)) {
      ...
  }

PHP 7.2

All features.

• object pseudo-type: function f(object $o) (in addition to bool, int, float, string, array, iterable, callable, self, parent and interface/class name (and mixed since PHP 8.0)).
• Abstract method overriding:

  abstract class A
  {
      abstract public function f(string $x);
  }
  
  abstract class B
  {
      // Maintaining contravariance for parameters and covariance for return
      abstract public function f($x): int;
  }

PHP 7.3

All features.

• New functions:
  • array_key_first()
  • array_key_last()
  • is_countable()
  • ...
• Array destructuring supports reference assignments: [&$id, &$name] = $data[0].

PHP 7.4

All features.

• Null coalescing assignment operator: $array['key'] ??= 'initial value'.
• Typed properties: private int $id.
• Arrow functions: fn($n) => $n * $factor, where $factor is a parent scope variable.
• Unpacking inside arrays: $fruits = ['banana', 'orange', ...$otherFruits].
• Numeric literal separator: 299_792_458; // Decimal number.

PHP 8.0

All features.

• mixed pseudo-type: function parse_int(mixed $input) (in addition to bool, int, float, string, array, object, iterable, callable, self, parent and interface/class name).
• static return type: public static function get_instance(): static {}.
• Named arguments: parse_int($input, max: 10).
• Union types: function validate_int(mixed $input): int|false.
  • But not false, false|null or ?false prior to PHP 8.2 (see the caution).
• Constructor property promotion (declaring properties in the constructor signature):

  class Point
  {
      public function __construct(private int $x, private int $y = 0) {}
  }

• Nullsafe operator (?->): get_booking(31)?->get_price() ?? 0.0.
• Support for Attributes has been added.
• Posibility to fetch the class name of an object using $object::class. The result is the same as get_class($object).
• Added Stringable interface.
  • Automatically implemented if a class defines a __toString() method.
• Traits can now define abstract private methods (must be implemented by the class using the trait).
• throw can be used as an expression: $user = $session->user ?? throw new Exception('Must have user.');.
• An optional trailing comma is allowed in parameter lists:

  function f(
      $parameter1,
      $parameter2, // This comma is now allowed
  )

• It is possible to write catch (Exception) without storing it in a variable.
• New methods/functions:
  • DateTime::createFromInterface()
  • preg_last_error_msg()
  • str_contains()
  • str_starts_with()
  • str_ends_with()
  • ...

PHP 8.1

• never return-only type indicating the function does not terminate: calls exit(), throws an exception, or is an infinite loop.
  • Cannot be part of a union type declaration.