PHP 裡的 Prototype-based 開發手法
上次介紹了一篇 Bring some Ruby/Prototype flavour in your PHP array ，這次有個類似的。
文章網址： Prototype-based programming in PHP
原文轉載如下：
For those who have been doing a lot of Javascript programming, you know what prototype-based programming is all about. The basic idea is that functions can be added to classes dynamically. In Javascript functions can be added to a static class (using prototype) and it will be added to all instances of the class, or they can be added to a specific instance and only be added to that instance.
Anyway, lets get to the point. I decided to try adding this functionality to PHP. I’m not sure why its a good idea, or if it even is, but I’ll let you be the judge of that. So here is the class I came up with:
/**
* @copyright © 2006, Schmalls / Joshua Thompson, All Rights Reserved
* @license http://www.opensource.org/licenses/bsd-license.php New BSD
* @author Joshua Thompson <spam.goes.in.here@gmail.com>
* @version 1.0.0
* @link http://www.countercubed.com
*/
/**
* This class holds the prototype capabilities
*
* Extending this class makes it prototype capable
*/
class Prototype
{
/**
* Holds prototype functions
*
* @var array
*/
private $_functions = array();
/**
* Default constructor
*
* This is here so that php doesn't complain about the prototype function
*/
public function __construct()
{
}
/**
* Sets the prototype functions or variables
*
* @param string $name
* @param mixed $value
*/
public function __set( $name, $value )
{
if ( function_exists( $value ) ) :
$this->_functions[$name] = $value;
else :
$this->$name = $value;
endif;
}
/**
* Gets static prototype variables if they exist
*
* @param string $name
* @return mixed
*/
public function __get( $name )
{
if ( isset( $this->prototype()->$name ) ) :
return $this->prototype()->$name;
else :
trigger_error( 'Undefined property: ' . __CLASS__ . '::' . $name, E_USER_NOTICE );
endif;
}
/**
* Calls a static prototype function
*
* @param string $name
* @param array $arguments
* @return mixed
*/
public function __call( $name, $arguments )
{
if ( isset( $this->_functions[$name] ) ) :
return call_user_func_array( $this->_functions[$name], $arguments );
elseif ( $this->prototype()->isCallable( $name ) ) :
return call_user_func_array( array( $this->prototype(), $name ), $arguments );
else :
trigger_error( 'Call to undefined method ' . __CLASS__ . '::' . $name . '()', E_USER_ERROR );
endif;
}
/**
* Returns the static prototype holder
*
* @return Prototype
*/
public static function prototype()
{
static $prototype = null;
if ( $prototype === null ) :
$prototype = new Prototype();
endif;
return $prototype;
}
/**
* Needed for the static calling functionality
*
* @return boolean
*/
public function isCallable( $name )
{
return ( isset( $this->_functions[$name] ) );
}
}
Now all a class needs to do is extend the Prototype class. A sample of its use follows:
// make some prototype classes
class Test1 extends Prototype
{
}
class Test2 extends Prototype
{
}
class Test3 extends Test1
{
}
// lets create some test static functions
Test1::prototype()->fun1 = create_function( '$arg1', '
echo \'Static Test1::fun1 \' . $arg1 . "\n";
');
Test2::prototype()->fun2 = create_function( '$arg1', '
echo \'Static Test2::fun2 \' . $arg1 . "\n";
');
// now instantiate the objects
$test1 = new Test1();
$test2 = new Test2();
// and make some more functions
$test1->fun3 = create_function( '$arg2', '
echo \'Test1::fun3 \' . $arg2 . "\n";
');
$test2->fun4 = create_function( '$arg2', '
echo \'Test2::fun4 \' . $arg2 . "\n";
');
// output: Static Test1::fun1 bob
$test1->fun1( 'bob' );
// create another function
Test1::prototype()->fun2 = create_function( '$arg1', '
echo \'Static Test1::fun2 \' . $arg1 . "\n";
');
// output: Static Test1::fun2 bobby
$test1->fun2( 'bobby' );
// output: Static Test2::fun2 robert
$test2->fun2( 'robert' );
// output: Test1::fun3 robby
$test1->fun3( 'robby' );
// output: Test2::fun4 rob
$test2->fun4( 'rob' );
// another instance still has the static functions
$test1_2 = new Test1();
// output: Static Test1::fun1 bob
$test1_2->fun1( 'bob' );
$test3 = new Test3();
// this will give an error because prototype functions do not extend down to a child class
$test3->fun1( 'roberto' );
Once again, I don’t know how useful it is, but let me know what you think.
主要的概念是用 PHP5 的 magic methods ： __set 、 __get 、 __call 。
利用 __set 及物件內部的 _functions 變數記住 create_function 所產生出來的 callback 匿名函式，然後再用 __call 呼叫這些動態建立的 methods 。
當然 magic methods 必須在物件實體產生後才能使用，詳細的說明可以參考一下該文回應的部份。