PHP multidimensional array type hinting for function parameter

Question

In PHP, is it possible to type hint a multidimensional array as a function parameter?

Of course you can type hint a single array as such:

function Example(array $parameter) {}

But if a function needs the parameter to be a multidimensional array is there any way to enforce this through type hinting?

Answer 1

If by DoubleArray you meant an Array of Doubles (Floats) only. Then you may want to fake it using a Custom Class. Consider the Code below. Notice that the initial Array Contains strings but the final results doesn't:

<?php

    class DoubleArray{
        protected $instance;
        public function __construct(array $arrDoubles) {
            foreach($arrDoubles as $key=>$double) {
                if(!is_double($double)){
                    unset($arrDoubles[$key]);
                }
            }
            $this->instance = array_values($arrDoubles);
        }

        public function push($numDouble){
            $this->instance[] = $numDouble;
        }

        public function get(){
            return $this->instance;
        }
    }

    $arr    = array(2.35, 72.9, 88.45, 42.76, "No...", 57.77,  "String is not Double");
    $da     = new DoubleArray($arr);

    var_dump(getData($da));


    function getData(DoubleArray $data){
        // ALL ARRAY FUNCTIONS STILL APPLY TO THE $doubleArray VARIABLE
        // HOWEVER TO GET THE CUSTOM DOUBLE ARRAY DATA, YOU MAY HAVE TO
        // JUST CALL THE get() METHOD ON THE DoubleArray INSTANCE: $data
        $doubleArray    = $data->get();
        return $doubleArray;
    }

    // THE var_dump(getData($da); ABOVE PRODUCES:
    array (size=5)
      0 => float 2.35
      1 => float 72.93
      2 => float 88.45
      3 => float 42.76
      4 => float 57.77

However, if by DoubleArray you meant Multidimensional Arrays , you can still fake it using a Custom Class as illustrated below.

<?php

    class DoubleArray{
        protected $instance;

        public function __construct(array $arrMDDoubles) {
            foreach($arrMDDoubles as $key=>$subArray) {
                if(!is_array($subArray)){
                    throw new Exception("DoubleArray accepts only Multidimensional Arrays...");
                }
            }
            $this->instance = $arrMDDoubles;
        }

        public function push($arrArray, $key=null){
            if(!is_array($arrArray)){
                throw new Exception("You can only Push an Array...");
            }
            if(!is_null($key)){
                $this->instance[$key]   = $arrArray;
            }else{
                $this->instance[]       = $arrArray;
            }
            return $this;
        }

        public function get(){
            return $this->instance;
        }
    }

    $arr    = array(array(2.35, 72.93,), array(88.45, 42.76), array("No...", 57.77,  "String is not Double"));
    $da     = new DoubleArray($arr);

    var_dump(getData($da));


    function getData(DoubleArray $data){
        // ALL ARRAY FUNCTIONS STILL APPLY TO THE $doubleArray VARIABLE
        // HOWEVER TO GET THE CUSTOM DOUBLE ARRAY DATA, YOU MAY HAVE TO
        // JUST CALL THE get() METHOD ON THE DoubleArray INSTANCE: $data
        $doubleArray    = $data->get();
        return $doubleArray;
    }

    // THIS TIME THE THE var_dump(getData($da) ABOVE WOULD THROW AN EXCEPTION
    // IF THE GIVEN ARRAY IS NOT MULTI-DIMENSIONAL BUT PRODUCE SOMETHING
    // LIKE THIS OTHERWISE:     
    array (size=3)
      0 => 
        array (size=2)
          0 => float 2.35
          1 => float 72.93
      1 => 
        array (size=2)
          0 => float 88.45
          1 => float 42.76
      2 => 
        array (size=3)
          0 => string 'No...' (length=5)
          1 => float 57.77
          2 => string 'String is not Double' (length=20)