PHP 5.3: New Language Features
Sebastian Bergmann
July 14th 2009

Who I am
 Sebastian Bergmann
 Involved in the PHP
project since 2000
 Creator of PHPUnit
 Co-Founder and
Principal Consultant
with thePHP.cc

PHP 5.3
New Language Features
 Lambda Functions
 Closures
 Functors
 Late Static Binding
Namespaces
 goto

PHP 5.3
Other Improvements
 New extensions
 phar, intl, fileinfo
 Garbage Collector
 MySQL Native Driver
 Improved Windows support

PHP 5.3
Performance Improvements
30
20
10
0
PHP 5.0.5 PHP 5.1.6 PHP 5.2.10 PHP 5.3.0

Lambda Functions
In a nutshell
Anonymous functions that
 are declared on-the-fly,
 can be assigned to a variable,
 and passed to other functions

Lambda Functions
Usage
<?php
$function = function() { print 'Hello World!'; };
?>

Lambda Functions
Usage
<?php
$function = function() { print 'Hello World!'; };
$function();
?>
Hello World!

Lambda Functions
Usage
<?php
$function = function() { print 'Hello World!'; };
call_user_func($function);
?>
Hello World!

Lambda Functions
Usage
<?php
$function = function() { print 'Hello World!'; };
call_user_func_array($function, array());
?>
Hello World!

Lambda Functions
Usage Scenarios
<?php
$list = array(22, 4, 19, 78);
usort(
$list,
function ($a, $b) {
if ($a == $b) return 0;
return ($a < $b) ? -1 : 1;
}
);
print_r($list);
?>
Array
(
[0] => 4
[1] => 19
[2] => 22
[3] => 78
)

Lambda Functions
Usage Scenarios
<?php
print_r(
array_map(
function ($n) { return($n * $n * $n); },
array(1, 2, 3, 4, 5)
)
);
?>
Array
(
[0] => 1
[1] => 8
[2] => 27
[3] => 64
[4] => 125
)

Lambda Functions
Prior to PHP 5.3
<?php
$function = create_function('', 'print "Hello World!";');
$function();
?>
Hello World!

Lambda Functions
Prior to PHP 5.3
<?php
$function = create_function('', 'print "Hello World!";');
call_user_func($function);
?>
Hello World!

Lambda Functions
Prior to PHP 5.3
<?php
$function = create_function('', 'print "Hello World!";');
call_user_func_array($function, array());
?>
Hello World!

Closures
In a nutshell
Anonymous functions that
 are declared on-the-fly,
 can be assigned to a variable,
 passed to other functions,
 and remember what happens around them

Closures
Lexical Variables
<?php
$string = 'Hello World!';
$function = function() use ($string) { print $string; };
$function();
?>
Hello World!

Closures
Lexical Variables
<?php
$plus_this = function($num) {
return function($arg) use ($num) {
return $arg + $num;
};
};
print_r(
array_map(
$plus_this(100), array(1, 2, 3)
)
);
?>
Array
(
[0] => 101
[1] => 102
[2] => 103
)

Closures
Y-Combinator
<?php
function Y($F) {
$func = function ($f) {
return $f($f);
};
return $func(
function ($f) use($F) {
return $F(
function ($x) use($f) {
$ff = $f($f);
return $ff($x);
}
);
}
);
}
http://en.wikipedia.org/wiki/Fixed_point_combinator

Closures
Lexical Variables with references
<?php
$x = 1;
$function = function() use ($x) { print $x . "n"; };
$function();
$x = 2;
$function();
print "n";
$x = 1;
$function = function() use (&$x) { print $x . "n"; };
$function();
$x = 2;
$function();
?>
1
1
1
2

Closures
Reflection API
<?php
$function = function($a, $b) { return $a + $b; };
$reflector = new ReflectionFunction($function);
print $reflector;
?>
Closure [ <user> function {closure} ] {
@@ /home/sb/closure_reflection.php 2 - 2
- Parameters [2] {
Parameter #0 [ <required> $a ]
Parameter #1 [ <required> $b ]
}
}

Functors
In a nutshell
 Allow an object to be invoked or called as
if it were an ordinary function
 Can be used to implement stateful
callbacks
 Also called function objects, functionals or
functionoids

Functors
Usage
<?php
class Example {
public function __invoke() {
print __METHOD__ . "n";
}
}
$object = new Example;
$object();
?>
Example::__invoke

Static Binding
Early Static Binding
<?php
class Base
{
public static function a()
{
print __METHOD__ . "n";
self::b();
}
public static function b()
{
print __METHOD__ . "n";
}
}
class Child extends Base
{
public static function b()
{
print __METHOD__ . "n";
}
}
Child::a();
?>
Base::a
Base::b

Static Binding
Late Static Binding
<?php
class Base
{
public static function a()
{
print __METHOD__ . "n";
static::b();
}
public static function b()
{
print __METHOD__ . "n";
}
}
class Child extends Base
{
public static function b()
{
print __METHOD__ . "n";
}
}
Child::a();
?>
Base::a
Child::b

Namespaces
Declaration
a.php
<?php
namespace project;
const ANSWER = 42;
class SomeClass {}
function do_something() {}
?>

Namespaces
Fully qualified names
a.php
<?php
namespace project;
const ANSWER = 42;
class SomeClass {}
function do_something() {}
?>
b.php
<?php
require 'a.php';
print projectANSWER;
$object = new projectSomeClass;
projectdo_something();
?>

Namespaces
Import from namespace into local scope
a.php
<?php
namespace project;
const ANSWER = 42;
class SomeClass {}
function do_something() {}
?>
c.php
<?php
require 'a.php';
use projectSomeClass;
$object = new SomeClass;
?>

Namespaces
Import from namespace into local scope (conflict)
a.php
<?php
namespace project;
const ANSWER = 42;
class SomeClass {}
function do_something() {}
?>
c.php
<?php
class SomeClass {}
require 'a.php';
use projectSomeClass;
?>
Fatal error: Cannot use projectSomeClass as SomeClass because the
name is already in use in /tmp/c.php on line 6

Namespaces
Import from namespace into local scope with alias
a.php
<?php
namespace project;
const ANSWER = 42;
class SomeClass {}
function do_something() {}
?>
d.php
<?php
class SomeClass {}
require 'a.php';
use projectSomeClass as Foo;
?>

The End
Thank you for your interest!
These slides will be posted on
http://slideshare.net/sebastian_bergmann

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