Errors when parameters are passed by reference

[bradynpoulsen]

DI\Container::make fails silently and returns null when provided argument is not provided by reference, but the dependency expects it to be passed by reference. In example

class A
{
}

class B
{
    public function __construct(A &$aInstance, SomeOtherDependencies $baz)
    {
    }
}

$foo = $container->get('A');
// do some stuff to $foo
try
{
    $bar = $container->make('B', [
        'aInstance' => $foo
    ]);
}
catch(DependencyException $e)
{
    // never gets fired
}
echo is_object($bar) ? get_class($bar) : gettype($bar); // prints 'NULL'

$barReal = $container->make('B', [
    'aInstance' => &$foo
]);
echo is_object($bar) ? get_class($bar) : gettype($bar); // prints 'B'

Whereas, DI\FactoryInterface defines that a DI\DependencyException will be thrown when there is an error while resolving the entry; however, the exception is not thrown

Whereas, \ReflectionParameter::isPassedByReference() is available to check if the parameter should be passed by reference

Therefore,

1. DI\Container::make should throw a DI\DependencyException if DI\Definition\Resolver\ObjectCreator::createInstance is unable to provide an object of a class after calling \ReflectionClass::newInstanceArgs(array $args)
2. I believe the DI\Definition\Resolver\ParameterResolver::resolveParameters() should check if \ReflectionParameter::isPassedByReference() is true

[mnapoli]

Hi, thanks for the report.

1. DI\Container::make should throw a DI\DependencyException

Yep definitely agree. I have to admit I have never used the container with parameters passed by reference, I'm surprised it doesn't even throw an exception but I've never tested it :/

Ideally though it should work and not throw an exception or return null.

2. I believe the DI\Definition\Resolver\ParameterResolver::resolveParameters() should check if \ReflectionParameter::isPassedByReference() is true

to check if the parameter should be passed by reference

The parameter doesn't need to be passed by reference when creating the instance. It's already marked with & in the method declaration, it just needs to be passed as a normal parameter. Maybe it doesn't work because it's using the reflection… I need to look into it, I can't say right now. See also this example:

class A {
    public $foo;
}

class B {
    public function __construct(A &$a) {
        $a->foo = 'hello';
    }
}

$a = new A();
$b = new B($a);
echo $a->foo; // hello

[bradynpoulsen]

Following up on checking \ReflectionParameter::isPassedByReference():

DI\Definition\Resolver\ParameterResolver has multiple locations that it would loose it's reference. Please see lines #62, #65, and #91.

Is my understanding of those assignment statements in PHP correct? I apologize that I didn't clarify that in my initial suggestion.

[mnapoli]

OK I see what you meant! Indeed the reference might be lost at points like that, I was thinking of the actual method/constructor call.