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7. PHP 7/8+ New Features

What are Named Arguments (introduced in PHP 8.0)?​

Junior

Answer: Named arguments allow you to pass values by parameter name instead of position, making the code more readable and allowing you to skip optional parameters.

htmlspecialchars($string, double_encode: false);

What are Union Types (introduced in PHP 8.0)?​

Junior

Answer: Union types allow you to specify multiple types for a parameter, property, or return value, instead of just one.

function sum(int|float $a, int|float $b): int|float {
    return $a + $b;
}

What are Match Expressions (introduced in PHP 8.0)?​

Junior

Answer: A safer and more concise alternative to switch that uses strict comparison and returns a value.

$status = match($code) {
    200, 201 => 'success',
    default => 'unknown',
};

What is the #[Override] attribute (introduced in PHP 8.3)?​

Junior

Answer: The #[Override] attribute ensures that a method with the same name exists in a parent class or interface. This helps catch errors during refactoring.

class Child extends ParentClass {
    #[Override]
    public function existingMethod() {}
}

What is the json_validate() function (introduced in PHP 8.3)?​

Junior

Answer: Checks if a string is a valid JSON without decoding it, which uses less memory.

if (json_validate($jsonString)) {
    // string is valid JSON
}

What is dynamic class constant fetch (introduced in PHP 8.3)?​

Junior

Answer: A simplified syntax to fetch class constants using a variable.

$name = 'STATUS_ACTIVE';
echo MyClass::{$name};

What are the null, false, and true standalone types (introduced in PHP 8.2)?​

Junior

Answer: These can now be used as standalone types for return values, parameters, and properties.

public function alwaysFalse(): false { return false; }

What is the Nullsafe Operator (introduced in PHP 8.0)?​

Junior

Answer: The ?-> operator allows you to safely access properties or methods on a potentially null value without throwing an error.

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

What are the new array functions introduced in PHP 8.4?​

Junior

Answer: PHP 8.4 introduced four new functions for searching and validating array elements using a callback: array_find(), array_find_key(), array_any(), and array_all().

$firstEven = array_find([1, 2, 3, 4], fn($v) => $v % 2 === 0); // 2
$anyEven = array_any([1, 3, 5], fn($v) => $v % 2 === 0); // false

What are the array_first() and array_last() functions (introduced in PHP 8.5)?​

Junior

Answer: PHP 8.5 added native functions to get the first and last elements of an array without moving the internal array pointer.

$arr = ['a' => 1, 'b' => 2, 'c' => 3];
$first = array_first($arr); // 1
$last = array_last($arr);   // 3

What is the new class instantiation syntax in PHP 8.4?​

Junior

Answer: PHP 8.4 allows accessing properties and methods of a newly instantiated class without needing to wrap the new expression in parentheses.

// Before PHP 8.4
$name = (new User())->getName();

// PHP 8.4
$name = new User()->getName();

What are the main differences between PHP 5.x and PHP 7/8?​

Middle

Answer: The transition from PHP 5 to PHP 7/8 brought significant improvements in performance, security, and developer experience.

Key Improvements in PHP 7/8:

  • Performance: PHP 7 is up to twice as fast as PHP 5.6, and PHP 8 introduced JIT (Just-In-Time) compilation for further speed gains in certain workloads.

  • Scalar Type Declarations: PHP 7/8 supports strict typing for int, float, bool, and string.

  • Return Type Declarations: You can now specify the return type of a function.

  • Null Coalescing Operator (??): Provides a shorthand for checking if a value is set and not null.

  • Spaceship Operator (<=>): Used for combined comparisons (less than, equal to, or greater than).

  • Anonymous Classes: Support for creating classes on the fly.

  • Improved Error Handling: Many fatal errors were converted to exceptions in PHP 7, and PHP 8 introduced the Error class hierarchy.

  • Match Expressions (PHP 8): A more powerful and strict version of switch.

  • Named Arguments (PHP 8): Allows passing arguments by name.

  • Enums (PHP 8.1): Support for enumerations.

  • Readonly Properties (PHP 8.1): Properties that cannot be modified after initialization.

  • First-class Callable Syntax (PHP 8.1): Simplified syntax for function references.

  • Readonly Classes (PHP 8.2): Entire classes can be marked as readonly.

  • DNF Types (PHP 8.2): Combine union and intersection types.

  • #[Override] Attribute (PHP 8.3): Ensure a method overrides a parent method.

  • Typed Class Constants (PHP 8.3): Add type hints to class constants.

  • json_validate() (PHP 8.3): Check if a string is valid JSON without decoding.

  • Property Hooks (PHP 8.4): Support for computed properties with get and set hooks.

  • Asymmetric Visibility (PHP 8.4): Different visibility for reading and writing properties.

  • New Array Functions (PHP 8.4): array_find(), array_find_key(), array_any(), and array_all().

  • Simplified Class Instantiation (PHP 8.4): Create class and call method/property without extra parentheses: new User()->name.

  • Pipe Operator (PHP 8.5): New operator (|>) for chaining function calls.

  • URI Extension (PHP 8.5): A new built-in extension for URI parsing and manipulation.

  • array_first() and array_last() (PHP 8.5): Get first and last elements of an array.

  • #[\NoDiscard] Attribute (PHP 8.5): Warn when return value of a function is not used.

  • PIE (PHP 8.5+): Official PHP Installer for Extensions replaces PECL.

  • Detailed PHP 8.0 Features

  • Detailed PHP 8.1 Features

  • Detailed PHP 8.2 Features

  • Detailed PHP 8.3 Features

  • Detailed PHP 8.4 Features

  • Detailed PHP 8.5 Features

What are Enums (introduced in PHP 8.1)?​

Middle

Answer: Enumerations allow you to define a set of named constants, providing type safety for fixed sets of values.

enum Status: string {
    case Pending = 'pending';
    case Active = 'active';
}

What are Readonly Properties (introduced in PHP 8.1)?​

Middle

Answer: Properties that cannot be modified after they are initialized.

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

What is the First-class callable syntax (introduced in PHP 8.1)?​

Middle

Answer: A simplified syntax to get a reference to any function or method.

$fn = strlen(...);
echo $fn('hello'); // 5

What is the never return type (introduced in PHP 8.1)?​

Middle

Answer: Indicates that a function will never return normally (it either throws an exception or calls exit()).

function redirect(string $url): never {
    header("Location: $url");
    exit;
}

What are Typed Class Constants (introduced in PHP 8.3)?​

Middle

Answer: Class constants can now have type declarations, similar to properties and parameters.

class User {
    const string ROLE = 'admin';
}

What is Constructor Property Promotion (introduced in PHP 8.0)?​

Middle

Answer: A shorthand syntax to define and initialize class properties directly in the constructor.

class User {
    public function __construct(public string $name, public int $age) {}
}

What are Property Hooks (introduced in PHP 8.4)?​

Middle

Answer: Property hooks allow defining custom logic for getting and setting class properties directly on the property declaration, reducing the need for explicit getter and setter methods.

class User {
    public string $name {
        get => strtoupper($this->name);
        set => strtolower($value);
    }
}

What is the Pipe Operator (introduced in PHP 8.5)?​

Middle

Answer: The pipe operator (|>) allows passing the result of an expression as the first argument to a function or method, making it easier to chain multiple transformations.

$result = "  hello world  "
    |> trim(...)
    |> strtoupper(...)
    |> (fn($str) => str_replace('WORLD', 'PHP 8.5', $str));
// Result: "HELLO PHP 8.5"

What are Readonly Classes (introduced in PHP 8.2)?​

Senior

Answer: Marking a class as readonly makes all its properties readonly and prevents dynamic properties.

readonly class Post {
    public function __construct(public string $title) {}
}

What are Disjunctive Normal Form (DNF) Types (introduced in PHP 8.2)?​

Senior

Answer: Allows combining union and intersection types. Intersection types must be grouped with parentheses.

public function process((A&B)|null $entity) { ... }

What are Intersection Types (introduced in PHP 8.1)?​

Senior

Answer: Allow declaring that a parameter or return value must implement multiple interfaces or classes simultaneously.

public function count(Countable&Iterator $it) { ... }

What are Fibers (introduced in PHP 8.1)?​

Senior

Answer: A way to create lightweight coroutines for non-blocking I/O and asynchronous tasks. They allow pausing and resuming execution within a single thread.

What is Asymmetric Visibility (introduced in PHP 8.4)?​

Senior

Answer: It allows setting different visibility levels for reading and writing a property. This is typically used to have a property that is publicly readable but can only be modified from within the class (private set).

class User {
    public private(set) string $id;
}

What is the #[\NoDiscard] attribute (PHP 8.5)?​

Senior

Answer: It's a new built-in attribute that indicates the return value of a function or method must be used. Static analysis tools and some IDEs will warn if the result of such a function is ignored.

#[\NoDiscard]
function calculateImportantValue(): int {
    return 42;
}

calculateImportantValue(); // Static analysis warning: Return value ignored.

What is PIE and how it relates to PECL?​

Senior

Answer: PIE (PHP Installer for Extensions) is the modern, official tool for installing PHP extensions, designed to replace the legacy PECL (which is now deprecated). It's distributed as a PHAR (like Composer) and works similarly, using PHP Foundation's repository.

# Example usage
pie install redis