PHP Attributes

This package provides an easy way to use and apply PHP 8 Attributes and allows quick real-world implementations meta-data or annotation related features like Routes, Events, DB Relations.

Features

• Apply PHP 8 attributes to a class and class components
• Automatically apply attributes to autoloaded classes
• Restrict attributes to filter condition of class name, namespace or class reflection

See Upcoming features of next release.

Concept

php-attributes uses a decorated composer autoloader and notifies a handler with loaded class name. The attributes for class components get resolved using reflections.

This package supports attributes for

• classes
• class constants
• class methods
• class method parameters
• class properties.

Install

Via Composer

$ composer require mbunge/php-attributes

Usage

Instantiate the attribute handler Mbunge\PhpAttributes\AttributeResolver via factory PhpAttributes\PhpAttributesFactory::createResolver() or direct.

Attributes of traget class components get resolved by passed class name as string to Mbunge\PhpAttributes\Resolver\AttributeResolver::resolve(string $class).

All resolved attributes returned as an array of data-transfer object (dto) Mbunge\PhpAttributes\Resolver\ResolvedAttributesDto.

<?php

use Mbunge\PhpAttributes\PhpAttributesFactory;

// instantiate via factory
$handler = (new PhpAttributesFactory())->createResolver();

// instantiate direct
$handler = new Mbunge\PhpAttributes\AttributeResolver();

/** @var \Mbunge\PhpAttributes\Resolver\ResolvedAttributeDto[] $result */
// via string
$result = $handler->resolve('\MyProject\MyClassWithAttributes');

// or via class name
$result = $handler->resolve(\MyProject\MyClassWithAttributes::class);

Run multiple resolver

\Mbunge\PhpAttributes\Resolver\ChainedAttributeResolver receives a list of resolvers, execute each resolver and merge reolved results.

This is usefull when resolvers with different contexts need to execute at once.

<?php

use Mbunge\PhpAttributes\Resolver\ChainedAttributeResolver;

$resolvers = [
    new CustomAttributeResolver(),
    new AnotherAttributeResolver(),
    // ...
];

$resolver = new ChainedAttributeResolver($resolvers);

// receive results from CustomerAttributeResolver and AnotherAttributeResolver
$results = $resolver->resolve('MyProject\AnyClass');

Restrict attributes to filter condition of class name, namespace or class reflection

Mbunge\PhpAttributes\Resolver\FilterClassAttributeResolverDecorator decorates an instance of attribute handler with any callable filter.

<?php

use Mbunge\PhpAttributes\Resolver\FilterClassAttributeResolverDecorator;

// instantiate base handler
$handler = new Mbunge\PhpAttributes\AttributeResolver();

// instantiate filter decorator with filter given as callable
$decoratedResolver = new FilterClassAttributeResolverDecorator(
    $handler,
    fn(string $className) => str_starts_with($className, 'MyProject')
);

// Attribute resolves only if filter condition matches
$result = $decoratedResolver
    ->resolve(\MyProject\MyClassWithAttributes::class);

See FilterClassAttributeResolverDecoratorTest for filter examples

Present resolved attributes

Resolved attributes provide declared meta-data.

Pass resolved attributes to presenter and perform context specifc actions.

Examples

All examples use a small Application implementation.

• auto-subscribe event listeners with event dispatcher aware presenter.

Chain presenters

\Mbunge\PhpAttributes\Presenter\ChainedAttributePresenter receives a list of presenters, execute each presenter and merge results.

This is usefull when attributes needs to present to different contexts, like application routeing, event dispatcher, etc.

See ChainedAttributePresenterTest for detailed implementation.

Attribute handler

Avoid blueprint code and use handler to resolve attributes and present them afterwards.

<?php

use Mbunge\PhpAttributes\AttributeHandler;
use Mbunge\PhpAttributes\PhpAttributesFactory;

/** @var ClassLoader $loader */
$loader = require __DIR__ . '/vendor/autoload.php';

// optionally pass a handler to handler
// You may add custom handler behaviour or a custom handler at this point
$handler = new AttributeHandler(
    (new PhpAttributesFactory())->createResolver(),
    new NullAttributePresenter()
);

$handler->handle('MyProject\MyClass');

Automatically apply attributes to autoloaded classes

The libray provides a composer classloader decorator which extends composer autoloader with the ability to execute attribute handler when class got autoloaded.

See also packaged autoload.

<?php

use Composer\Autoload\ClassLoader;
use Mbunge\PhpAttributes\AttributeHandler;
use Mbunge\PhpAttributes\LoaderHandler;
use Mbunge\PhpAttributes\PhpAttributesFactory;

/** @var ClassLoader $loader */
$loader = require __DIR__ . '/vendor/autoload.php';

// optionally pass a handler to handler
// You may add custom handler behaviour or a custom handler at this point
$attributeHandler = new AttributeHandler(
    (new PhpAttributesFactory())->createResolver(),
    new NullAttributePresenter()
);

$handler = new LoaderHandler($attributeHandler);

return $handler->handle($loader);

// optionally avoid unregister of previous autoloader
// it is recommanded to keep only one autoloader, since previous autoloader will be unreachable
return $handler->handle($loader, false);

Use packaged autoload

Replace composer default autoload /vendor/autoload with packaged autoload /vendor/mbunge/php-attributes/autoload.php

The packed autoload applies all attributes to autoloaded classes.

<?php

require_once __DIR__ . '/vendor/mbunge/php-attributes/autoload.php';

Caveats

PHP 8 Attributes will not solve all problems.

Automatically apply logic through meta-data declarations sounds cool, but requires a lot of convention and my lead into complexity and may be hard to debug!

SOLID may get violated as well, since attributes are some sort of dependecy. Use attributes only for helpful tasks and without violating clean code priciples!

Furthermore, it is helpful to provide cli tools for attribute analytics and debugging.

Change log

Please see CHANGELOG for more information on what has changed recently.

Testing

$ composer test

Contributing

Please see CONTRIBUTING and CODE_OF_CONDUCT for details.

Deployment

Only maintainers are allowed to deploy new versions!

1. Run composer run release which will run tests and on success update changelog, package version and creates a release tag
2. switch to master branch and merge develop branch
3. Run composer run deploy which will run tests and on success push tags, master branch and develop branch

Security

If you discover any security related issues, please email [email protected] instead of using the issue tracker.

Credits

• Marco Bunge
• All Contributors

License

The MIT License (MIT). Please see License File for more information.

Further read

• In-depth PHP Attributes by stitcher.io: https://www.stitcher.io/blog/attributes-in-php-8