$this->load->function(parameter) - what is is ?

[adresanet]

Hi,

Reading CodeIgnitier documentation I saw some statements having this form:
$this->someword->somefunction();
and I don't know what is that.

Is someword an multi-dimensional/associative array?
I know that if I create an instance of a class I can access its properties and functions with a single -> operator or with :: operator.
But I don't know what means usage of 2 -> parameters.

Thanks!

[whitespace]

Well, you would seem to know the answer already, although it's not an "array", it's a class instance (an object).

I know that if I create an instance of a class I can access its properties and functions with a single -> operator...

It's really the same thing...

someword is a property of the current class ($this refers to the current class) that holds a class instance. somefunction is a method of that class instance.

At some point earlier in the code a class instance has been assigned to the property someword.

There's no limit to how "deep" you can go...

$someVar->A->B->C->D->methodOfD();

Where A, B, C and D are all class properties that hold an instance of a class.

[adresanet]

Thank you for your response!
If you can please write for me a class implementation and usage so I can understand exactly how I can use them.

[whitespace]

An example... an AddressBook class and an Emailer class, which sends an email to a user whose ID is found in the AddressBook.

We only use the object/arrow operator here since we are dealing with instantiated classes (objects). The :: (double colon OR scope resolution operator) is used to reference static properties and methods (or classes directly... classes which have not been instantiated).

/**
 * Our address book class
 */
class AddressBook implements IAddressBook {
  /**
   * Get the fullname of the passed user
   * @param string $userId A registered user's ID
   */
  public function getFullname($userId) {
    $fullname = null;
    /* Lookup users fullname for user $userId, throw Exception on error, etc. */
    return $fullname;
  }
  public function getEmailAddress($userId) {
    $emailAddr = null;
    /* Lookup primary email address for user $userId */
    return $emailAddr;
  }
  public function getTelephoneNumber($userId) {
    /* Etc. */
  }
}

/**
 * A class for emailing users (from our address book)
 */
class Emailer {
  /**
   * Class property holds an instance of our address book
   * which is passed into the constructor (when the class is instantiated)
   */
  protected $_addressBook = null;

  /**
   * Default "From" address
   *  - Override in extended class
   */
  protected $_fromAddress = '[e-mail]';

  /**
   * Class constructor
   * @param IAddressBook $addressBook An instance (ie. object) of our address book
   */
  public function __construct(IAddressBook $addressBook) {
    // Assign passed object to our class property
    // "this" is a special variable referring to the current class instance
    $this->_addressBook = $addressBook;
  }

  /**
   * Send welcome email to user
   * @param string $userId A registered user's ID of the user we wish to send the email to
   */
  public function sendWelcome($userId) {
    // ** MAGIC **
    // Lookup details about user in our address book
    $userName = $this->_addressBook->getFullname($userId);
    $userEmail = $this->_addressBook->getEmailAddress($userId);

    $body = <<<EOD
Hi $userName,
Welcome to WebmasterWorld!
EOD;
  }
    mail($userEmail, 'Welcome to WebmasterWorld', $body, 'From: '.$this->_fromAddress);
}

// Instantiate the AddressBook
$addressBook = new AddressBook();

// Instantiate the Emailer, passing our already instantiated AddressBook to the constructor
$emailer = new Emailer($addressBook);

// Send a welcome email to a user whose ID is...
$emailer->sendWelcome('whitespace');

Not sure why the syntax highlighting appears to have stopped half way through the code? (The forum appears not to be able to handle it correctly?!)

[whitespace]

Btw, search for "MAGIC" in the above code block to see the use of the double -> (object/arrow) operator.

[adresanet]

Thank you!
It is very clear now for me. Actually it has some logic, but at first I was scared of it :)