Variable Scope in PHP MVC Frameworks like CakePHP - php

Question

I am building a PHP MVC framework like Ruby on Rails but with PHP for learning. The link just in case you want to see it is https://github.com/carlinoo/vinum
I was trying to see the source code of CakePHP as it is very similar to mine. When in aa action in a controller, after the logic of that action/method, it calls the view, a different file that has access to those variables. I cant seem to understand how that works.
How does it call the view after the logic is finished? In CakePHP there’s something called autoRender that if set to true, it renders the appropriate view. How can you do that without calling a function to render the view?
Also, I have a variable scope problem. Let me explain:
function func1() {
$var = 1;
render();
}
function render() {
require_once(‘file.php’);
}
// This is file.php
<?php
echo $var;
?>
$var one does not exist because of the scope, and i don’t want to declare the variables as global. How do big PHP Frameworks do this? And how does the autoRender actually work? Thank you

Answer 1

This is the "easy" way
function func1() {
$var = 1;
render(‘file.php’, get_defined_vars());
}
function render($file, $vars = []) {
extract($vars);
require $file; //pass the filename in for reuse
}
But it's really messy, and prone to variable name collisions.
This function returns a multidimensional array containing a list of all defined variables, be them environment, server or user-defined variables, within the scope that get_defined_vars() is called.
http://php.net/manual/en/function.get-defined-vars.php
Import variables from an array into the current symbol table.
http://php.net/manual/en/function.extract.php
I would manually build an array of variables, pass that to render($vars) and then use extract().
function func1() {
$vars = ['var1' => 1];
render(‘file.php’, $vars);
}
Also I would use require instead of require_once otherwise if you need to render the same template multiple times it wont work, think like in the case of a post or something you can loop on and call render multiple times. For example
you may have a "controller" named posts.php
render('header.php');
render('menu.php');
foreach($posts as $post){
render('post.php', $post);
}
render('footer.php');
The main Idea behind a template is to eliminate structural PHP mixed into the HTML. So you would want, smaller chunks of HTML that you can reuse multiple times. And mostly keep it to echoing variables in the tempate/view
Lastly, I would take what I put above as "theoretical" code, I can't really test this very well, but that's the basic concept.
UPDATE
Here is a quick Psudo-ish Code example of what CakePHP does ( obviously its way more complex then i can do in an answer on here ).
Its mainly the difference between using procedural and object oriented coding.
class Controller{
protected $data;
public function index(){
$this->color = 'pink';
$this->render('view.php');
}
///magic method
public function __set( $key, $value){
$this->data[$key] = $value;
}
/*
you can do the same thing with a normal method
public function set( $key, $value){
$this->data[$key] = $value;
}
but instead of doign $this->color = 'pink';
you would do $this->set('color', 'pink');
*/
public function render($file){
/*
obviously I can easily access $this->data['color']
from within the scope of the same class.
*/
extract($this->data);
include $file;
/*
or any number of other things
like
$contents = file_get_contents($file);
foreach( $this->data as $key => $value )
$contents = str_replace('{'.$key.'}', value , $contents);
echo $contents;
for tags like {color} etc.
*/
}
}
Right here is every method they are using.
https://api.cakephp.org/3.5/class-Cake.Controller.Controller.html
And here is the source code for their controller,
https://api.cakephp.org/3.5/source-class-Cake.Controller.Controller.html#583-622
Honestly I wouldn't recommend using the magic metods like __set __get etc. because it Makes the code
harder to read
harder to maintain
more prone to error
less efficient, performance wise.
For example
$this->set('data', 'foo');
Is safe, but using
$this->data = 'foo';
Will wipe out that data array property, because in my example the data gets put into a class property named data as an array, so calling $this->data = foo; accesses the already existing property and overwrites it. Which then means you have to do all kinds of checks and other things to make sure nothing gets overwritten, and anytime you add any properties you have to deal with that kind of stuff. And if you miss something you may not find it for months and then one day, you set data in a controller and it all falls apart.
For reference.
http://php.net/manual/en/language.oop5.magic.php
Anyway