CHAPTER 3 - public, protected, and private Methods

3.6.2 public, protected, and private Methods
Access modifiers may also be used in conjunction with object methods, and the
rules are the same:
public methods can be called from any scope.
protected methods can only be called from within one of its class methods
or from within an inheriting class. private methods can only be called from within one of its class methods
and not from an inheriting class. As with properties, private methods
may be redeclared by inheriting classes. Each class will see its own ver-
sion of the method:
class MyDbConnectionClass {
public function connect()
{
$conn = $this->createDbConnection();
$this->setDbConnection($conn);
return $conn;
}
protected function createDbConnection()
{
return mysql_connect(”localhost”);
}
private function setDbConnection($conn)
{
$this->dbConnection = $conn;
}
private $dbConnection;
}
class MyFooDotComDbConnectionClass extends MyDbConnectionClass {
protected function createDbConnection()
{
return mysql_connect(”foo.com”);
}
}
This skeleton code example could be used for a database connection class.
The connect() method is meant to be called by outside code. The createDbCon-
nection() method is an internal method but enables you to inherit from the
class and change it; thus, it is marked as protected. The setDbConnection()
method is completely internal to the class and is therefore marked as private.
Note: When no access modifier is given for a method, public is used as the
default. In the remaining chapters, public will often not be specified for this
reason.