Back To Class - New Cars For Old
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Now that you've got the concepts straight, let's take a look at the nitty-gritty of a class definition.
<?
class Automobile
{
// this is where the properties are defined
var $colour;
var $shape;
...
// this is where the functions are defined
function start()
(
// code goes here
)
...
}
?>
Every class definition begins with the keyword "class",
followed by a class name. You can give your class any name that strikes your fancy, so long as it doesn't collide with a reserved PHP word. A pair of curly braces encloses all class variables and functions, which are written as you would normally code them.
In order to create a new instance of a class, you need to use the "new" keyword, and assign the newly-created object to a PHP variable.
<?
$his = new Automobile;
?>
In English, the above would mean "create a new object of
class Automobile and assign it to the variable $his".
You can now access all the methods and properties of the class via this variable.
<?
// accessing properties
$his->make = "Ferrari";
$his->colour = "Black";
// accessing methods
$his->start();
$his->accelerate(180);
?>
Again, in English,
$his->make = "Ferrari";
would mean
"assign the value Ferrari to the variable
$make of this specific instance of the class Automobile", while
$his->accelerate(180);
would mean
"execute the function accelerate() with
parameter 180 of this specific instance of the class Automobile".
Note the -> symbol, and the fact that the $ symbol is omitted when accessing variables of a specific class instance.
Next: Ford's Law >>
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