PHP 5.4.0 is released by the PHP development team with a large number of new features and bug fixes today.

New features of PHP 5.4.0

• Support of Traits
• Short array syntax
• Improved performance and reduced memory consumption
• Better support for multibyte languages at runtime switch
• Built-in webserver for development and/or testing

Removal of deprecated features

• Magic quotes has been removed to avoid security issues
• Register globals directives have been removed
• Safe mode is no longer supported in terms of security

Backward incompatible changes

• The break and continue statements no longer accept variables
• Removal of session_is_registered(), session_register() and session_unregister() functions
• default_charset now defaults to UTF-8 instead of ISO-8859-1

Deprecated features in PHP 5.4

• mysql_list_dbs()
• get_magic_quotes_gpc()
• get_magic_quotes_runtime()
• mcrypt_generic_end()

New functions in PHP 5.4

• hex2bin()
• http_response_code()
• get_declared_traits()
• trait_exists()
• header_register_callback()

Traits

First of all, it looks like a multiple inheritance like some of the other languages. Methods and properties from the Traits are being ‘merged’ into the class so you can’t have same name or will cause a fatal error. Take a look at the Conflict Resolution section in Traits on how to resolve this issue with the insteadof operator.

<?php
trait Hello {
    public function sayHello() {
        echo 'Hello ';
    }
}

trait World {
    public function sayWorld() {
        echo ' World';
    }
}

class MyHelloWorld {
    use Hello, World;
    public function sayExclamationMark() {
        echo '!';
    }
}

$o = new MyHelloWorld();
$o->sayHello();
$o->sayWorld();
$o->sayExclamationMark();

The above example will output:

Hello World!

Short Array Syntax

You can now replace array() with just [].

<?php
$arrTest1 = [1, 2, 3, 4];

$arrTest2 = ['a' => 'one', 'b' => 'two', 'c' => 'three', 'd' => 'four'];

Built-in Web Server

The CLI SAPI provides a built-in web server, mainly for development and testing purposes.

Kindly visit Built-in webserver for more information.

Conclusion

If you are interested in the full list of changes, kindly visit the ChangeLog in PHP site.