Assign array type in PHP

Question

I know PHP is a weakly typed language. But there is some alternative way to "type" a array in PHP?

Example, I can do this below to force receive a specific type of data in a function.

function exemplo(Classe $valor){
    // meu código aqui ...
}

However, I would like to know how to do something similar as in Java (see below) with lists.

List<String> array = new ArrayList<>;

There is a way to do this in PHP?

Answer 1

Is not possible.

PHP was dynamically and weakly typed, in the background nothing has fixed type. All arrays PHP accepts that any element has any type. It can be mixed at will. It is an inherent feature of this type of language. There is no syntax or option in the compiler that can force or even indicate what kind of data the elements can have. That is they will always be Mixed according to the PHP definition.

Already Hack which is an evolution of PHP created by Facebook allows Generics and the "arrays" can be typed. Although it is based on PHP, it is another language.

It is possible partially in PHP since version 7, and in 7.4 this becomes stronger, but it is done in a bad way because it has the legacy without type.

Answer 2

Actually there is a way to type php even though it is dynamically typed. Take a look at this link http://php.net/manual/en/function.settype.php

To type php you must do so:

settype($foo, "integer");

So assuming $foo is the whole kind. As the friend above mentioned there is the hack language that works with a typed "php", I have performed some tests in the language, but I do not think still mature enough to abandon the good old php.

Answer 3

This is also something that always bothered me not knowing the types of elements I have inside an array.

The implementation I decided to do was to extend the Class Iteratoriterator PHP. This class asks for an Iterator interface to be injected and so it uses its methods by the magic method __call. What was done was to create an input method for the elements with the typed parameter and insert another Arrayiterator class input method (offsetSet) as private.

So I made this code.

  
class TestArrayIterator extends IteratorIterator {

    private $arrayIterator;

    public function __construct() {
        $this->arrayIterator = new ArrayIterator();
        parent::__construct($this->arrayIterator);
    }

    public function append(IElement $element) {
        $this->offsetSet(null, $element);
    }

    private function offsetSet($key, IElement $element) {
        $this->arrayIterator->offsetSet($key, $element);
    }

}

interface IElement {

    public function getCodigo();
    public function getNome();

}

class Element implements IElement {

    private $codigo;
    private $nome;

    public function setCodigo($codigo) {
        $this->codigo = $codigo;
    }

    public function setNome($nome) {
        $this->nome = $nome;
    }

    public function getCodigo() {
        return $this->codigo;
    }

    public function getNome() {
        return $this->nome;
    }
}

$element = new Element();
$element->setCodigo(1);
$element->setNome('nome 1');

$element_1 = new Element();
$element_1->setCodigo(2);
$element_1->setNome('nome 2');


$testIterator = new TestArrayIterator();
$testIterator->append($element);
$testIterator->append($element_1);

foreach ($testIterator as $key => $element) {   
    echo $key . ' - ' . $element->getCodigo() . ' => ' . $element->getNome() . "\n";    
}