Three characteristic functions in PHP5

The three characteristic functions of PHP5. The three main features are:

* New Object mode
* Exception Handling (Exceptions)
* Namespace (Namespace)
　　
Before you begin, declare two points:
* Examples in the article to illustrate how to operate, some parts of the use of PHP4 performance means, this is only to improve the readability of the article.
* There may be some discrepancies between the sections described in the article and the final release of PHP5
Before the PHP5 is officially released, you can download it from http://snaps.php.net to the latest compiled version to personally experience the new features that PHP5 brings to us.
　　
The new object pattern
　　
The objects in the PHP5 have been systematically and comprehensively tuned, and may now look somewhat similar to Java. This section focuses on the new object patterns in PHP5, with some simpler examples to illustrate. Let this section be a new starting point for your PHP5 journey. ：）
　　

* Constructors and destructors
* References to Objects
* Cloning of objects
* Private, public, and protected mode in the object
* Interface (interfaces)
* Abstract class
* __call
* __set and __get
* Static member
　　
Constructors and destructors
　　
In PHP4, when a function has the same name as an object, the function becomes the constructor of the object, and there is no concept of destructors in the PHP4.
　　
In PHP5, constructors are uniformly named __construct, and the concept of destructors is introduced, which is uniformly named __destruct.
　　
Example one: constructors and destructors
　　

Code fragment
<?php
class Foo {
var $x;
function __construct ($x) {
$this->x = $x;
}
function display () {
Print ($this->x);
}
function __destruct () {
Print ("Bye Bye");
}
}
$o 1 = new Foo (4);
$o 1->display ();
?>

In the above example, when you terminate the call to the Foo class, its destructor will be invoked, and the "Bye Bye" will be printed in the example above.
　　
References to Objects
　　
As we all know, in the PHP4, passing a variable to a function or method, which actually makes a copy of the variable, means that you pass a copy of the variable to the function or method, unless you use the reference symbol "&" to declare a reference, not a copy. In PHP5, an object is always in the form of a reference, and the assignment operation in the object is also a reference operation.
　　
Example two: A reference to an object
　　

Code fragment
<?php
class Foo {
var $x;
function SetX ($x) {
$this->x = $x;
}
function GetX () {
return $this->x;
}
}
$o 1 = new Foo;
$o 1->setx (4);
$o 2 = $o 1;