Technically Callable Reflection

Technically\CallableReflection is a handy library to simplify reflecting any callable. It provides a unified interface for reading callable arguments seamlessly supporting PHP8 union types. It also lets you to easily invoke a callable with call() and apply() supporting named parameters.

Features

• Unified and simplified interface to reflect callable parameters
• No dependencies
• Supports PHP 8.0, 8.1, 8.2, 8.3, 8.4 (supports union types, mixed, false, etc; see examples below)
• PHP 7.1+ compatible — runs on as low as PHP 7.1
• Semver
• Tests

Installation

Use Composer package manager to add Technically\CallableReflection to your project:

composer require technically/callable-reflection

Examples

Reflecting callable properties

<?php
$function = function (string $abstract, Closure|string|null $concrete): mixed {
    // function body
};

$reflection = CallableReflection::fromCallable($function);

var_dump($reflection->isFunction()); // false
var_dump($reflection->isMethod()); // false
var_dump($reflection->isClosure()); // true

[$p1, $p2] = $reflection->getParameters();

var_dump($p2->getName()); // "concrete"
var_dump($p2->isNullable()); // true
var_dump($p2->isOptional()); // false
var_dump($p2->hasTypes()); // true

[$t1, $t2, $t3] = $p2->getTypes();

var_dump($t1->isScalar()); // false 
var_dump($t1->isClassName()); // true 
var_dump($t1->getType()); // "Closure" 

var_dump($t2->isScalar()); // true 
var_dump($t2->isClassName()); // false 
var_dump($t2->getType()); // "string"

var_dump($t3->isNull()); // true
var_dump($t3->isScalar()); // false 
var_dump($t3->isClassName()); // false 
var_dump($t3->getType()); // "null" 

Reflecting arbitrary class constructor

<?php
final class MyService {
    public function __construct(LoggerInterface $logger, bool $debug = false)
    {
        // ...
    }
}

$reflection = CallableReflection::fromConstructor(MyService::class);

var_dump($reflection->isConstructor()); // true
var_dump($reflection->isFunction()); // false
var_dump($reflection->isMethod()); // false
var_dump($reflection->isClosure()); // false

[$p1, $p2] = $reflection->getParameters();

var_dump($p1->getName()); // "logger"
var_dump($p1->isNullable()); // false
var_dump($p1->isOptional()); // false
var_dump($p1->hasTypes()); // true

var_dump($p2->getName()); // "debug"
var_dump($p2->isNullable()); // false
var_dump($p2->isOptional()); // true
var_dump($p2->hasTypes()); // true

Checking if value satisfies parameter type declaration

$function = function (int|string $value = null): mixed {
    // function body
};

$reflection = CallableReflection::fromCallable($function);

[$param] = $reflection->getParameters();

var_dump($param->satisfies(null)); // true
var_dump($param->satisfies(1)); // true
var_dump($param->satisfies('Hello')); // true
var_dump($param->satisfies(2.5)); // false
var_dump($param->satisfies([])); // false
var_dump($param->satisfies(true)); // false

Invoking callable via reflection

$function = function (string $abstract, Closure|string|null $concrete): mixed {
// function body
};

$reflection = CallableReflection::fromCallable($function);

// 1) call with positional parameters
$result = $reflection->call(LoggerInterface::class, MyLogger::class);

// 1) call with named parameters
$result = $reflection->call(concrete: MyLogger::class, abstract: LoggerInterface::class);

// 2) call with positional parameters array 
$result = $reflection->apply([LoggerInterface::class, MyLogger::class]);

// 3) call with named parameters array 
$result = $reflection->apply(['concrete' => MyLogger::class, 'abstract' => LoggerInterface::class]);

// 4) call with mixed named and positional parameters array 
$result = $reflection->apply([LoggerInterface::class, 'concrete' => MyLogger::class]);

// 5) CallableReflection is a callable by itself
$result = $reflection(LoggerInterface::class, MyLogger::class);

Invoking constructor via reflection

final class MyService {
    public function __construct(LoggerInterface $logger, bool $debug = false)
    {
        // ...
    }
}

$reflection = CallableReflection::fromConstructor(MyService::class);

$service = $reflection->call(new NullLogger());
// or alternatively:
// $service = $reflection->apply(['logger' => new NullLogger()]);
assert($service instanceof MyService);

How is this better than reflecting Closure::fromCallable()

This library's functionality is somewhat similar to what a reflection of the standard Closure::fromCallable() can provide. And if that's enough for your use case, you probably want to be using the standard reflection.

This library, however, does provide some added value on top:

• It unifies interactions with all kinds of callables, including class constructors. That was actually the primary use case I had in mind for it — building a DI service container.

  For example, you cannot instantiate a new instance with Closure::fromCallable():

  $reflection = new ReflectionFunction(Closure::fromCallable([MyRemoteService::class, '__construct']));
  $service = $reflection->call($token); // (!) doesn't work

  but you can call a constructor with this library:

  $reflection = CallableReflection::fromConstructor(MyRemoteService::class);
  $service = $reflection->call($token);

• It provides utilities to check if a specific value satisfies the given function argument type declaration (see ->satisfies()).

• It can know and tell what type of callable was reflected, while with Closure::fromCallable() this information is lost. This might be important for certain use cases.

• It has nice additional convenience getters and checkers. Like satisfies(), isOptional(), isNull(), isScalar(), etc.

• The API is more intuitive and straighforward and hides away PHP version differences introduced to the Reflections API over years. The native Reflections API is polluted with BC-preserving constructs.

• The library is operating on top of the native Reflections API, and therefore is as performant as it is, plus a little overhead for the convenience wrappers.

Changelog

All notable changes to this project will be documented in the CHANGELOG file.

Credits

Implemented by 👾 Ivan Voskoboinyk.