Page 182 - Open Soource Technologies 304.indd

Web Technologies-I

Notes If you are familiar with JavaScript, it should be obvious by now that the -> operator plays the
same role in PHP as the dot operator in JavaScript. For example, in JavaScript, this produces
the date for Christmas Day 2011:

var xmas2011 = new Date(2011, 11, 25); // months are zero-based alert(‘Christmas 2011 is on
‘ + xmas2011.toString());

JavaScript also uses the dot operator for properties:
objectName.propertyName
If you are familiar with the basics of OOP in PHP, you should recognize that you often access
class data and functionality through objects. For instance, you should be familiar with the syntax:
$Foo = new Foo();

$Foo->Name = “Navneet”;
The above snippet alters the public member variable Name in class Foo. However, with the
introduction of the static keyword in PHP 5, we can now access methods and properties through
the context of a class rather than only the object (note: these methods/properties need to be declared
static first).

class Foo {
static public $Name = “Pradip kumar”;

static public function helloWorld() {
print “Hello world from “ . self::$Name;
}

}
To declare a method or property as static, we must use the static keyword. When accessing
properties from outside the class scope, we use the class name followed by two: and then the
property name. For instance:

print Foo::$Name . “\n”;
Foo::helloWorld();

The above would output:
Pradip kumar
Hello world from Pradip kumar

As static methods are within the class scope, they cannot access any normal methods or properties
(i.e. those that have not been declared static), as those would belong to the object, and not the
class. A by-product of this is you cannot use the $this variable from within a static method, as
static methods are not invoked in the context of an object.

You should be able to see that from within the context of the class, to access
member variables or properties you use the self keyword.

176 LOVELY PROFESSIONAL UNIVERSITY