WHat's new in PHP 8.0

MergePHP November 2020

Ian Littman / @iansltx

follow along at https://ian.im/php8merge

ETA: November 26, 2020 (two weeks!)

RC4 is out now

Thanks to release managers Sara Golemon and Gabriel Caruso

What we'll cover

• Where to get it now
• What's new
• What's deprecated/removed
• How to find out more information

How do I get it?

• macOS (nightly builds)
  • brew tap shivammathur/php
  • brew install shivammathur/php/php@8.0
• Ubuntu/Debian instructions (aka use Ondrej's repo)
• Red Hat-based: use Remi's repo
• Inside Docker: e.g. php:8.0.0RC4-fpm-alpine3.12
• Windows builds can be downloaded here
• Source code to build yourself is on php.net

Just in Time COmpiler (JIT)

• Useful for heavy computation
• Less impactful when you're spending your time waiting for other services
• CLI tools will run faster (e.g. exakat is ~15% faster)
• Web workloads...probably not (but maybe with e.g. AMPHP?)

Union Types

function query(
    PDO|PDOInterface $db, // same syntax as multi-catch
    string $query,
    ?array $params = []
): array|int {
    // do stuff
}

Stringable interface

function query(
    PDO|PDOInterface $db,
    string|Stringable $query, // anything with __toString()
    ?array $params = []
): array|int {
    // do stuff
}

Mixed Typehint

interface DoesAThing {
    function doAThing(mixed $thisCouldBeAnything): mixed;

# string|int|float|bool|null|array|object|callable|resource
}

Named parameters

query(query: 'SELECT 1', db: $pdo);

query(
    $pdo,
    params: ['one', 'two'],
    query: 'SELECT * FROM notes WHERE slug IN (?, ?)'
);

If you're writing a library, you have a whole new class of BC breaks to think about.

NullSafe Operator

interface NoteRepo {
    public function findBySlug(string $slug): ?Note;
}
class Note   { public Author $author; }
class Author { public string $name; }

$notes->findBySlug('nonexistent')?->author->name; // ?string

Match Expressions

switch (getRoute()) {
    case '/home':
    case '/':
        $title = 'Home Page';
        break;
    case '/profile':
        $title = getUserName();
        break;
    default:
        $title = 'My Great App!';
}

$title = match (getRoute()) {
    '/home', '/' => 'Home Page',
    '/profile' => getUserName(),
    default => 'My Great App!'
};

Class Constructor Property Promotion

class DbColumn
{
    public function __construct(
        private string $name,
        private bool $nullable = false
    ) {
        echo $this->name . ' is '
            . ($nullable ? '' : 'not ')
            . "nullable\n";
    }
}

Attributes

#[Attribute]

class DbColumn {
    public function __construct(
        private string $name,
        private bool $nullable = false
    ) {}
}

class Note {
    #[DbColumn('name')]
    public string $name;
}

$dbColumn = (new ReflectionClass('Note'))
    ->getProperties()[0] // $name property
    ->getAttributes()[0] // DbColumn ReflectionAttribute
    ->newInstance(); // DbColumn object with properties set

Catches with no exception variable

try {
    $api = API::connect();
    // do stuff with $api
} catch (BadApiKey) {
    // The type of the exception is enough to decide what
    // to do here, so we don't need the exception itself.
}

New functions | Methods!

• fdiv() - float division with INF/-INF returned for division by 0
• get_debug_type() - more accurate gettype() (names match typehints)
• str_contains(), str_starts_with(), str_ends_with() - returns booleans (vs. strpos)
• preg_last_error_msg() - friendlier message on why your regex match failed
• get_resource_id() - (int) $resource with type safety
• DateTime|DateTimeImmutable::createFromInterface()

String formatting additions

• %h, %H in printf format for locale-independent floats
• Precision/width modifiers in printf
• "p" TZ offset param for DateTime::format() to show UTC as "Z" vs. "+0000"
  So now you can use Y-m-d\TH:i:sp (existing constnts are unaffected)

...and a few more

BC Break Time

ValueError + more errors from internal functions

echo strpos('needle', 'haystack', 1337);
// Now: Throws a ValueError
// THen: Returned false and emitted a warning

String concatenation +/- Precedence

echo "Five plus three is " . 5 + 3;
// Now: "Five plus three is 8"
// Then: 3 (7.4 has a deprecation warning)

See https://3v4l.org/N2V4J

Resources -> Class Objects

• cURL handles -> Curl* classes
• GD resources -> GdImage
• Socket resources -> Socket or AddressInfo classes

Stricter implementation/extension type checking

trait Foo {
    abstract public function inParams(stdClass $item): array;
    abstract public function inReturn(stdClass $item): int;
}

class SuperFoo{
    use Foo;
    public function inParams(array $items): array{}
    //                       ^^^^^ Mismatch
    public function inReturn(stdClass $item): int{}
    //                                        ^^^ Mismatch
}

More fun with types

• Magic method signatures are now enforced
• Static calls to non-static methods now fail
• Required params after optional ones are now deprecated
• A few Reflection components are deprecated

Throwing and logging

• Asserts now throw rather than warn by default
• PDO now throws by default
• PHP startup errors are now displayed by default
• Default error level is now E_ALL
• Fatal errors now can't be silenced
• A bunch of warnings are now Errors, notices are warnings, etc.

...and a few more

• Salt is now required on crypt()
• substr now returns "" rather than false when working out-of-bounds
• Casting a string to a float is now locale-independent

Further Reading

• PHPBenelux Meetup - PHP 8 party edition (YT recording)
• php.watch/versions/8.0
• stitcher.io/blog/new-in-php-8

• ian.im/php8merge - these slides
• twitter.com/iansltx - me, online

Thanks! Questions?