php_new_syntax.md

PHP 7.0

Scalar type declarations: Allows functions to require certain types of arguments.
```
function sum(int $a, int $b) {
    return $a + $b;
}
```
Return type declarations: Allows functions to declare the type of the return value.
```
function sum($a, $b): int {
    return $a + $b;
}
```
Null coalescing operator (??): Returns its first operand if it exists and is not NULL; otherwise it returns its second operand.
```
$username = $_GET['user'] ?? 'nobody';
```
Spaceship operator (<=>): A three-way comparison operator. It returns -1, 0 or 1 when $a is respectively less than, equal to, or greater than $b.
```
echo 1 <=> 2;  // outputs -1
```
Constant arrays using define(): Defines an array as a constant.
```
define('ANIMALS', ['dog', 'cat', 'bird']);
```

PHP 7.1

Nullable types: Allows a type to be either a specified type or NULL.

function test(?string $name) {
    var_dump($name);
}
test(null);  // outputs NULL

Void functions: Specifies that a function should not return a value.
```
function test(): void {
    echo 'Hello, World!';
}
```

PHP 7.2

Object type: Allows for functions to accept any object as a parameter, or to return an object.
```
function test(object $obj): object {
    return new SplQueue();
}
```

PHP 7.3

Flexible Heredoc and Nowdoc Syntaxes: Allows for indenting of closing markers.
```
echo <<<END
    A indented heredoc syntax example.
END;
```

PHP 7.4

Typed Properties: Declares the type of a class property.

class User {
    public int $id;
    public string $name;
}

Arrow Functions: Allows for cleaner one-liner functions with implicit variable scope.
```
$factor = 10;
$nums = array_map(fn($n) => $n * $factor, [1, 2, 3, 4]);
```
Null coalescing assignment operator (??=): It's a shorthand for the common case of needing to use a ternary in conjunction with isset().
```
$data['date'] ??= '2023-01-01';
```

PHP 8.0

Named arguments: Allows passing arguments to a function based on the parameter name, instead of the parameter position.
```
htmlspecialchars($string, double_encode: false);
```

Constructor Property Promotion: Combines class properties and constructor parameters.

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

Match expression: A switch-like expression that can return values.

echo match (1) {
    0 => 'zero',
    1 => 'one',
    default => 'more',
};

Nullsafe Operator (?->): Allows for the chaining of method calls and property accesses even if one of the elements in the chain returns null.
```
$country = $session?->user?->getAddress()?->country;
```
Attributes (Annotations): Provides a way to add metadata to classes, methods, properties, parameters, and constants.
```
#[ExampleAttribute]
public function hello() {}
```
Union types: Allows a function to require arguments or return values of multiple types.
```
class Number {
    private int|float $number;
}
```

qwhex/php_new_syntax.md