Type hinting for properties in PHP 7?

Question

Does php 7 support type hinting for class properties?

I mean, not just for setters/getters but for the property itself.

Something like:

class Foo {     /**      *      * @var Bar      */     public $bar : Bar; }  $fooInstance = new Foo(); $fooInstance->bar = new NotBar(); //Error 

Answer 1

PHP 7.4 will support typed properties like so:

class Person {     public string $name;     public DateTimeImmutable $dateOfBirth; } 

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PHP 7.3 and earlier do not support this, but there are some alternatives.

You can make a private property which is accessible only through getters and setters which have type declarations:

class Person {     private $name;     public function getName(): string {         return $this->name;     }     public function setName(string $newName) {         $this->name = $newName;     } } 

You can also make a public property and use a docblock to provide type information to people reading the code and using an IDE, but this provides no runtime type-checking:

class Person {     /**       * @var string       */     public $name; } 

And indeed, you can combine getters and setters and a docblock.

If you're more adventurous, you could make a fake property with the __get, __set, __isset and __unset magic methods, and check the types yourself. I'm not sure if I'd recommend it, though.