Prototypes

The icanboogie/prototype package allows methods of classes using the PrototypeTrait to be defined at runtime, and since the icanboogie/accessor package is used, this also includes getters and setters.

Defining methods at runtime

Methods can be defined at runtime using the prototype of a class. They are immediately available to every instance of the class and are inherited by the sub-classes of that class.

<?php

use ICanBoogie\Prototype;
use ICanBoogie\PrototypeTrait;

class Cat { use PrototypeTrait; }
class OtherCat extends Cat {}
class FierceCat extends Cat {}

$cat = new Cat;
$other_cat = new OtherCat;
$fierce_cat = new FierceCat;
$second_fierce_cat = new FierceCat;

// define the 'meow' prototype method for Cat class
Prototype::from(Cat::class)['meow'] = function(Cat $cat) {

    return 'Meow';

};

// override the 'meow' prototype method for FierceCat class
Prototype::from(FierceCat::class)['meow'] = function(Cat $cat) {

    return 'MEOOOW !';

};

echo $cat->meow();               // Meow
echo $other_cat->meow();         // Meow
echo $fierce_cat->meow();        // MEOOOW !
echo $second_fierce_cat->meow(); // MEOOOW !

Defining getters and setters at runtime

Because getters and setters are methods too, they are defined just like regular methods.

<?php

use ICanBoogie\Prototype;
use ICanBoogie\PrototypeTrait;

class TimeObject
{
    use PrototypeTrait;

    public $seconds;
}

$time = new Time;
$prototype = Prototype::from(Time::class);

$prototype['set_minutes'] = function(Time $time, $minutes) {

    $time->seconds = $minutes * 60;

};

$prototype['get_minutes'] = function(Time $time, $minutes) {

    return $time->seconds / 60;

};

$time->seconds = 120;
echo $time->minutes; // 2

$time->minutes = 4;
echo $time->seconds; // 240

Dependency injection, inversion of control

Dependency injection and inversion of control can be implemented using prototype lazy getters.

The following example demonstrates how a magic image property can be defined to lazy load a record from an ActiveRecord model.

<?php

use ICanBoogie\Prototype;
use ICanBoogie\PrototypeTrait;

class Article
{
    use PrototypeTrait;

    public $image_id;
}

// …

Prototype::from(Article::class)['get_image'] = function(Article $target) use ($image_model) {

    return $target->image_id
        ? $image_model[$target->image_id]
        : null;

};

$article = new Article;
$article->image_id = 12;
echo $article->image->nid; // 12

Prototype methods and parent::

Prototype methods can be overridden and work with parent:: calls just like regular methods.

In the following example the prototype method url() is added to the class Node and overridden in the class News, still parent:: can be used from News:

<?php

use ICanBoogie\Prototype;
use ICanBoogie\PrototypeTrait;

class Node
{
    use PrototypeTrait;
}

class News extends Node
{
    public function url($type)
    {
        return parent::url("another/$type");
    }
}

Prototype::from(Node::class)['url'] = function($node, $type) {

    return "/path/to/$type.html";

};

$node = new Node;
$news = new News;

echo $node->url('madonna'); // /path/to/madonna.html
echo $news->url('madonna'); // /path/to/another/madonna.html

Defining prototypes methods

Prototype methods can be defined using a global configuration; through the prototype property of an Prototyped instance; or using the Prototype instance associated with classes using the PrototypeTrait trait.

Defining prototypes methods using a global configuration

All prototypes can be configured using a single global configuration. For each class you can define the methods that the prototype implements.

The following example demonstrate how the meow() method is defined for instances of the Cat and FierceCat classes. Although they are defined using closure in the example, methods can be defined using any callable such as "App\Hooks::cat_meow".

<?php

ICanBoogie\Prototype::bind([

    Cat::class => [

        'meow' => function(Cat $cat) {

            return 'Meow';

        }
    ],

    FierceCat::class => [

        'meow' => function(FierceCat $cat) {

            return 'MEOOOW !';

        }
    ]

]);

Defining prototypes methods through the prototype property

Prototype methods may be defined using the prototype property:

<?php

use ICanBoogie\PrototypeTrait;

class Cat
{
    use PrototypeTrait;
}

$cat = new Cat;

$cat->prototype['meow'] = function(Cat $cat) {

    return 'Meow';

};

echo $cat->meow();

Defining prototypes methods using a prototype instance

Prototype methods may be defined using the Prototype instance of a class:

<?php

use ICanBoogie\Prototype;

Prototype::from(Cat::class)['meow'] = function(Cat $cat) {

    return 'Meow';

};

Defining prototypes methods using config fragments

The preferred way to define prototype methods is with prototype configuration fragments, because they can be synthesised and cached.

The following example demonstrates how an application may bind a url() method and a url property to instances of ActiveRecord:

<?php

// config/prototype.php

namespace App;

$hooks = Hooks::class . '::';

return [

    Article::class . '::url' => $hooks . '::url',
    Article::class . '::get_url' => $hooks . '::url'

];

The following examples demonstrates how to retrieve the prototype configuration: 

<?php

namespace ICanBoogie;

require 'vendor/autoload.php';

$app = boot();
$app->configs['prototype'];

Getting an array representation of an object

An array representation of an Prototyped instance can be obtained using the to_array() method. Only public and façade properties are exported.

<?php

use ICanBoogie\Prototyped

class A extends Prototyped
{
    public $a;
    protected $b;
    private $c;

    public function __construct($a, $b, $c)
    {
        $this->a = $a;
        $this->b = $b;
        $this->c = $c;
    }

    protected function get_c()
    {
        return $this->c;
    }

    protected function set_c($value)
    {
        $this->c = $value;
    }
}

$a = new A('a', 'b', 'c');

var_dump($a->to_array());

// array(2) {
//  ["a"]=>
//  string(1) "a"
//  ["c"]=>
//  string(1) "c"
//}

As mentioned before, façade properties are also exported. The to_array() method should be overrode to alter this behavior.

Additionally the to_array_recursive() method can be used to recursively convert an instance into an array, in which case all the instances of the tree implementing ToArray or ToArrayRecursive are converted into arrays.

Getting a JSON representation of an object

The to_json() method can be used to get a JSON representation of an object. The method is really straight forward, it invokes to_array_recursive() and pass the result to json_encode().

<?php

echo $a->to_json(); // {"a":"a","c":"c"}

Creating an instance from an array of properties

The Prototyped::from() method creates an instance from an array of properties:

<?php

class A extends Prototyped
{
    private $a;
    protected $b;
    public $c;
}

$a = A::from([ 'b' => 2, 'c' => 3 ]);

Instances are created in the same fashion PDO creates instances when fetching objects using the FETCH_CLASS mode, that is the properties of the instance are set before its constructor is invoked.

Prototyped sub-classes might want to override the Prototyped::from method to allow creating instances from different kind of sources, just like the Operation::from method creates an Operation instance from a Request:

<?php

namespace ICanBoogie;

class Operation
{
    static public function from($properties = null, array $construct_args = [], $class_name = null)
    {
        if ($properties instanceof Request)
        {
            return static::from_request($properties);
        }

        return parent::from($properties, $construct_args, $class_name);
    }
}

Using the Prototype trait

The prototype features are available as a trait. Any class can implement them simply by using the PrototypeTrait trait.

<?php

use ICanBoogie\PrototypeTrait;

class MyException extends Exception
{
    use PrototypeTrait;

    private $a;
    private $b;

    public function __construct($a, $b, $message, $code=500, Exception $previous=null)
    {
        $this->a = $a;
        $this->b = $b;

        parent::__construct($message, $code, $previous);
    }

    protected function get_a()
    {
        return $this->a;
    }

    protected function get_b()
    {
        return $this->b;
    }

    protected function get_code()
    {
        return $this->getCode();
    }
}

$e = new MyException(12, 34, "Damned!", 404);

echo $e->a;    // 12
echo $e->b;    // 34
echo $e->code; // 404

$e->a = 34; // throws PropertyNotWritable

Exceptions

The following exceptions are defined: