Question

 1   <?php  
 2   class ACL  
 3   {  
 4       var $perms = array();        //Array : Stores the permissions for the user  
 5       var $userID = 0;            //Integer : Stores the ID of the current user  
 6       var $userRoles = array();    //Array : Stores the roles of the current user  
 7 
 8       function __constructor($userID = '')  
 9       {  
 10           if ($userID != '')  
 11          {  
 12               $this->userID = floatval($userID);  
 13           } else {  
 14               $this->userID = floatval($_SESSION['userID']);  
 15          }  
 16           $this->userRoles = $this->getUserRoles('ids');  
 17           $this->buildACL();  
 18       }  

This is part of a tutorial I’m learning creating a login system. I don’t know if I was at this for too long and my brain is fried but I’m getting confused about the boolean statement used as an argument in the function __constructor. See line 8.

This is the explanation given by the tutorial:

The __constructor() function is used to initialize the object when we
want to load an ACL. It is called automatically when we call new
ACL();. It is then passed a single, optional argument of the user to
load the ACL for. Inside the constructor, we check to see if a user ID
was passed in. If no ID was passed, we assume that we will load the
ACL for the currently logged in user; so we read in the session
variable for that. Alternatively, if we pass in a user ID, it allows
us to read and edit the ACL for a user other than the one logged in
(useful for your admin page).

Question #1… so this method is starting up as soon as you make a new class, and it is taking the boolean as an argument. I’m not understanding why you need to state the fact that userID = ‘ ‘. Couldn’t you just make it simpler and write: function __constructor($userID) { if ($userID != ”) ……..etc. etc. ?? Or do they mean the same thing?
The idea of stating a boolean never made sense to me, especially when you’re not using it in an IF statement to test it’s validity.

EDIT: I made a very weird slip. Sorry disregard the whole boolean thing, it’s not even a boolean statement. My error… 12 hours of learning programming is taking its toll.

Question 2: Is the variable $userID in line 5 the same as $userID in line8? I’m thinking no but I’m not sure. I’m sure that $userID on line 5 is the same as $this->userID on line 12 and line 15 but what about on line 8 and 10? I am confused. If the variable $userID on line 8 is NOT blank, then you are assigning $userID found on line 5 to the floatval of $userID on line 8??
I have a feeling that these are 2 different $userIDs. Why couldn’t this guy just use a different word if that’s the case? LOL

NOTE: I’ve been learning PHP for less than a week so these will seem like basic conceptual questions more than anything. Syntax isn’t really a problem for me, it’s the concepts.

Any help appreciated. Cheers.

Answer 1

Okay,

1. The method is not used every time you “make a new class”, it’s called every time an object is instantiated, meaning every time the new ClassName() statement is called. The reason function __construct($userID = '') is used and not function __construct($userID), is because we want to give it a default value. Meaning a user can either call new APC() or new APC("userID").
2. No. The one declared on line 5 is an object property, it’s a variable that exists within each object (meaning if you instantiate 2 APC classes, you would have one variable for each object created, 2 in total).
   The one on line 8 is a function argument. When the method is called with an argument (new APC("userID")) that argument will be stored in that variable inside of the function.
   It’s coincidental that both of them have the same name.