Type hinting in class variables

Question

<?php

namespace Sandbox;

class Sandbox {

    private Connectors\ISandboxConnector $connection;

    public function __construct(Connectors\ISandboxConnector $conn) {
        $this->connection = $conn;
    }

}

?>

For the above code I'm getting the following error:

Parse error: syntax error, unexpected 'Connectors' (T_STRING), expecting variable (T_VARIABLE)

When I remove the type hinting and var_dump that $connection variable, it will be private Sandbox\\Sandbox and not Sandbox\\Connectors\\ISandboxconnector , why?

Answer 1

PHP 7.3 and below does not support typed properties. You could only define a variable as below:

class Sandbox {
    private $connection;

However, to help editors understand your code, you may use a @var tag to document the expected type of the property:

class Sandbox {
    /** @var Connectors\ISandboxConnector */
    private $connection;

---

Update

PHP 7.4.0

Thanks @Manuel for mentioning the new update, PHP 7.4 now introduces typed properties according to PHP RFC: Typed Properties 2.0 .

Property type declarations support all type declarations supported by PHP, with the exception of void and callable . Any class or interface name, stdClass, scalar and compound types, references to parent and own objects are also supported.

class Sandbox {
    public int $id;
    public string $name;
    private Connectors\ISandboxConnector $connection;
}

Note: keep an eye on side effects such as uninitialised state and inheritance strict rules.

Answer 2

Since PHP 7.4 you are able to type hint on class properties, as shown here . So for example your $connection property would look like this:

class Sandbox {
    private Connectors\ISandboxConnector $connection;
}