How to avoid using PHP global objects?

Question

I'm currently creating blog system, which I hope to turn into a full CMS in the future.

There are two classes/objects that would be useful to have global access to (the mysqli database connection and a custom class which checks whether a user is logged in).

I am looking for a way to do this without using global objects, and if possible, not passing the objects to each function every time they are called.

Answer 1

You could make the objects Static, then you have access to them anywhere. Example:

myClass::myFunction();

That will work anywhere in the script. You might want to read up on static classes however, and possibly using a Singleton class to create a regular class inside of a static object that can be used anywhere.

Expanded

I think what you are trying to do is very similar to what I do with my DB class.

class myClass
{
    static $class = false;
    static function get_connection()
    {
     if(self::$class == false)
     {
      self::$class = new myClass;
     }
     else
     {
      return self::$class;
     }
    }
    // Then create regular class functions.
}

What happens is after you get the connection, using $object = myClass::get_connection(), you will be able to do anything function regularly.

$object = myClass::get_connection();
$object->runClass();

Expanded

Once you do that static declarations, you just have to call get_connection and assign the return value to a variable. Then the rest of the functions can have the same behavior as a class you called with $class = new myClass (because that is what we did). All you are doing is storing the class variable inside a static class.

class myClass
{
    static $class = false;
    static function get_connection()
    {
     if(self::$class == false)
     {
      self::$class = new myClass;
     }
     else
     {
      return self::$class;
     }
    }
    // Then create regular class functions.
    public function is_logged_in()
    {
     // This will work
     $this->test = "Hi";
     echo $this->test;
    }
}

$object = myClass::get_connection();
$object->is_logged_in();

Answer 2

Well, if you already have some object by which you refer to the blog system, you can compose these objects into that, so that they're $blog->db() and $blog->auth() or whatever.

Answer 3

You can take a look at the Design Pattern called "Singleton", and/or more specifically "Registry" (see this, for example)

If you are using a Framework, some have classes designed for that, like Zend_Registry

Answer 4

You could pass the currently global objects into the constructor.

<?php
  class Foo {
    protected $m_db;
    function __construct($a_db) {
      $this->m_db = $a_db;
    }
  }
?>