Question

A NEW UPDATE ON THE PROBLEM

I wan’t the class ‘BlogPost’ to access its parent class variables that have been set on the main.php page

class BlogPage {
    public $PageExists = false;
    public $PageTitle = "no title";
    public $PageId = "0";
    function __construct($page){
        //some sql to check if page exists
        if($page_exists){
            $this->PageExists = true;
            $this->PageTitle = $fetched['row_title'];
            $this->PageId = $fetched['row_id'];

        }
    }
}

class BlogPost extends BlogPage {
    function __construct(){
        $page_id = $this->PageId;
        //some sql to get the posts that have post_page like $page_id
    }
}

The Main.php page

$page = new BlogPage("index");
if($page->PageExists == true){
    include("posts.php");
}else{
include("notfound.php");
}

The posts.php

$pageTitle = $page->PageTitle;
$posts = new BlogPost();

?>

Answer 1

If you want to access parent’s class protected and public variables and functions, then you will use the parent:: static prefix.

In your case, if you want to access classOne‘s protected and public variables and functions inside classTwo, then you will just use parent:: inside classTwo.

If you just want to use the classTwo instantiated object on the included file, then you don’t need to declare it as global, you just access it normally as you would access it a few lines below declaring it on the main file.

Update 1

You don’t need to define the scope of that variable as global, because it already has that scope on that part of the script. So, just access it like this:

// global $page; remove this, no need for it
$pageTitle = $page->PageTitle;
$posts = new BlogPost();

Update 2

This is my suggested solution to your second problem:

<?php
class Page{
    public $PageExists  = false;
    public $PageTitle   = 'no title';
    public $PageId      = '0';
    // add other options here

    // add other parameters to this function
    // or pass an array to it
    protected function fill($page_id, $page_title){
        $this->PageExists   =   true;
        $this->PageId       =   $page_id;
        $this->PageTitle    =   $page_title;
    }
}

class BlogPage extends Page{
    function __construct($page){
        //some sql to check if page exists
        if($page_exists){
            parent::fill($fetched['row_id'], $fetched['row_title']);
        }
    }
}

class BlogPost extends Page {
    function __construct($page_id){
        //some sql to get the posts that have post_page like $page_id
        if($post_exists){
            parent::fill($fetched['row_id'], $fetched['row_title']);
        }
    }
}
?>

Then you can use your classes like the following…

On Main.php page

<?php
$page = new BlogPage("index");
if($page->PageExists == true){
    include("posts.php");
} else{
    include("notfound.php");
}
?>

On posts.php

<?php
$pageTitle  = $page->PageTitle;
$posts      = new BlogPost($page->PageId);
?>