the constructor method

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).

After we read in the user ID, we call getUserRoles() to generate an array of the roles the user is assigned to and store it in the $userRoles class variable. At the end of the constructor, we call buildACL() to generate the actual ACL. The method named ACL()is a crutch for PHP4 installs. When you call new ACL() in PHP5, the PHP interpreter runs the __constructor() method. However, when you run the same code in PHP4, the interpreter runs ACL(). By providing a method named the same as the class, we make the class PHP4 compatible.

Any time we create a new ACL object by passing in a user ID, that object will hold the permissions for the user who was passed in.

Helper Methods

Now, lets add some more helper methods to the same class file. These methods will provide support to the other methods by performing specialized tasks: