Programming PHP

You can use variable variables with property names:
$prop = 'age';
echo $rasmus->$prop;
A static method is one that is called on a class, not on an object. Such methods cannot
access properties. The name of a static method is the class name, followed by
two colons and the function name. For instance, this calls the p( ) method in the
HTML class:
HTML::p("Hello, world");
A class’s documentation tells you which methods are static.
Assignment creates a copyof an object with identical properties. Changing the copy
does not change the original:
$f = new Person('Fred', 35);
$b = $f; // make a copy
$b->set_name('Barney'); // change the copy
printf("%s and %s are best friends.\n", $b->get_name(), $f->get_name( ));
Barney and Fred are best friends.
Declaring a Class
To design your program or code library in an object-oriented fashion, you’ll need to
define your own classes, using the class keyword. A class definition includes the
class name and the properties and methods of the class. Class names are case-insensitive
and must conform to the rules for PHP identifiers. The class name stdClass is
reserved. Here’s the syntax for a class definition:
class classname [ extends baseclass ]
{
[ var $property [ = value ]; ... ]
}
[ function functionname (args) {
// code
}
...
]
Declaring Methods
A method is a function defined inside a class. Although PHP imposes no special
restrictions, most methods act onlyon data within the object in which the method
resides. Method names beginning with two underscores (__) maybe used in the
future byPHP (and are currentlyused for the object serialization methods _ _sleep( )
and _ _wakeup( ), described later in this chapter), so it’s recommended that you do
not begin your method names with this sequence.
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