Can a method be used as an array_map function

Question

I want to do something like this:

class Cls {
  function fun($php) {
    return 'The rain in Spain.';
  }
}

$ar = array(1,2,3);
$instance = new Cls();
print_r(array_map('$instance->fun', $ar));
               // ^ this won't work

but the first argument to array_map is supposed to be the name of the function. I want to avoid writing a wrapper function around $instance->fun, but it doesn't seem like that's possible. Is that true?

Callihan

Answer 1

Yes, you can have callbacks to methods, like this:

array_map(array($instance, 'fun'), $ar)

see the callback type in PHP's manual for more info

Camera

If the method is static array('Class', 'StaticMethod') works too – Lomeli

what if its an abstract class? which has the function to be called. – Scribner

@Scribner if it's a static function, you can use array('Class_Name', 'functionName') as the parameter. If it's the current class' parent class, then using array($this, 'functionName') should most likely work. – Camera

This does not work for me at all. $instance is undefined and $this uses the the object I'm calling array_map from. Could not find any way (except with a wrapper function) to refer to the objects in my array (I'm on php 5.4.7). – Berserk

@Berserk So you have an array containing objects, and you want to call a method on each of those? If so, that isn't something that can be done using array_map like this (or any other array function), as there is no way to refer to each object in the array. – Camera

@JaniHartikainen Thanks for clearing that. It looked to me as if that was, what the OP wanted to do. I ended up using a loop. – Berserk

if you're using namespaces, don't forget to use the full namespace. the following worked for me for static method: array_map('\App\Http\Response\AbstractResponse::convertBakedGood', $bakedGoods) – Anna

If called from inside a static class use: array('self', 'functionName') – Katricekatrina

Alternate if it's inside a static class: array(__CLASS__, 'functionName'); – Moises

what if the function fun requires more than 1 params? how to pass those extra params? – Involucel

Answer 2

You can also use

array_map('Class::method', $array) 

syntax.

Aposiopesis

This also works for the variation array_map('self::method', $array) – Pomace

Answer 3

Actually, you need to know the definition of Callback, please kindly refer to the following code:

<?php 

// An example callback function
function my_callback_function() {
    echo 'hello world!';
}

// An example callback method
class MyClass {
    static function myCallbackMethod() {
        echo 'Hello World!';
    }
}

$myArray = [1, 2, 3, 4];

// Type 1: Simple callback
array_map('my_callback_function', $myArray); 

// Type 2: Static class method call
array_map(array('MyClass', 'myCallbackMethod'), $myArray); 

// Type 3: Object method call
$obj = new MyClass();
array_map(array($obj, 'myCallbackMethod'), $myArray);

// Type 4: Static class method call (As of PHP 5.2.3)
array_map('MyClass::myCallbackMethod', $myArray);

// Type 5: Relative static class method call (As of PHP 5.3.0)
class A {
    public static function who() {
        echo "A\n";
    }
}

class B extends A {
    public static function who() {
        echo "B\n";
    }
}

array_map(array('B', 'parent::who'), $myArray); // A
?>

From: http://php.net/manual/en/language.types.callable.php

Charismatic

Answer 4

It worked for me as follows

<?php
class ExcelAutoFilterController extends Controller
{
    public function transpose($value):array
        {
            return [$value];
        }

        public function generateExcelDropdownDownload($file = 'helloWorld.xlsx')
        {

            $countries = [0 => "Algeria"1 => "Angola"2 => "Benin"3 => "Botswana"4 => "Burkina"5 => "Burundi"6 => "Cameroon"7 => "Cape Verde"8 => "Central African Republic"9 => "Chad"10 => "Comoros"11 => "Congo"12 => "Congo, Democratic Republic of"13 => "Djibouti"14 => "Egypt"15 => "Equatorial Guinea"16 => "Eritrea"17 => "Ethiopia"18 => "Gabon"19 => "Gambia"20 => "Ghana"21 => "Guinea"22 => "Guinea-Bissau"23 => "Ivory Coast"24 => "Kenya"25 => "Lesotho"26 => "Liberia"27 => "Libya"28 => "Madagascar"29 => "Malawi"30 => "Mali"31 => "Mauritania"32 => "Mauritius"];

            $countries = array_map('self::transpose', $countries);
        }
        

Ferdinand