How to detect null default value for non-typed class property via reflection in PHP?-CodePudding

When using reflection (ReflectionClass), is it possible to detect, whether a non-typed class property has a null default value specified, or has no default value at all?

class A {
    public $foo;
    public $bar = null;
}

Here, for both foo and bar, the ReflectionProperty::getDefaultValue() returns null and ReflectionProperty::hasDefaultValue() returns true.

$rc = new ReflectionClass(A::class);
var_dump($rc->getProperty("foo")->hasDefaultValue()); // true
var_dump($rc->getProperty("foo")->getDefaultValue()); // null
var_dump($rc->getProperty("bar")->hasDefaultValue()); // true
var_dump($rc->getProperty("bar")->getDefaultValue()); // null

How can I differentiate between the two properties?

CodePudding user response：

get_object_vars() should allow to make the difference

The documentation https://www.php.net/manual/en/function.get-object-vars.php says

Uninitialized properties are considered inaccessible, and thus will not be included in the array.

CodePudding user response：

Since php 7.4, class properties have an uninitialized state. This state is not the same as null:

class A {
    public string $foo;
}

$a = new A();
var_dump($a->foo === null);

Fatal error: Uncaught Error: Typed property A::$foo must not be accessed before initialization in ...

However, if there is no type declared the property will have null as its uninitialized value:

class B {
    public $foo;
}

$b = new B();
var_dump($b->foo === null); // true

You can use ReflectionProperty::isInitialized to check whether a property is initialized and ReflectionProperty::hasType to check if it has a type.