functions in a php router - php

Question

I have been trying to create a router for my php app,I am kinda new to mvc. I did some research and landed on a tutorial at requiremind.com that helped me do this. How ever there is this line of code that has been making me pull out my hair.
this is my code for the router.
<?php
function call($controller, $action) {
// require the file that matches the controller name
require_once('controllers/' . $controller . '_controller.php');
// create a new instance of the needed controller
switch($controller) {
case 'pages':
$controller = new PagesController();
break;
}
// call the action
$controller->{ $action }();
}
// just a list of the controllers we have and their actions
// we consider those "allowed" values
$controllers = array('pages' => ['home', 'error']);
// check that the requested controller and action are both allowed
// if someone tries to access something else he will be redirected to the error action of the pages controller
if (array_key_exists($controller, $controllers)) {
if (in_array($action, $controllers[$controller])) {
call($controller, $action);
} else {
call('pages', 'error');
}
} else {
call('pages', 'error');
}
?>
this is the part giving me headache $controller->{ $action }();.
The comment says it calls the action . But i do not have a function like action() anywhere.
I know there are different ways of creating a router but I would really want to understand how this particular one works.
I need someone to kindly help me understand what this part of the code does.

Answer 1

Use method_exists func
if(method_exists($controller, $action)) {
$controller->$action();
}

Answer 2

In this particular m-v-c application , looks like the author wanted the function call() to be the main function of the application , you analyze the request then call the function call with the appropriate controller and action. here is usage example of this code,
<?php
$path = trim(parse_url($_SERVER["REQUEST_URI"], PHP_URL_PATH), "/");
$pathParts = explode("/", $path);
switch ($pathParts[0]){
//www.example.com/home
case "home":
call("homePageController",'showPagefunction');
break;
//www.example.com/contact
case "contact":
if ($_SERVER['REQUEST_METHOD'] == "GET"){
call("contactPageController",'showPageFunction');
}else if($_SERVER['REQUEST_METHOD'] == "POST"){
call("contactPageController",'postContactMsgFunction');
}
break;
default:
header("HTTP/1.0 404 Not Found");
die("404 error");
}

Answer 3

That line calls a method named as specified in the value contained in the variable $action, so for example edit or delete. It is sometimes referred to as variable method call.
This answer was submitted by #arkaschar in the comments section