Prototype

Simple prototype-based programming in PHP

Prototype programming is a flavor of object-oriented programming that deals with objects without categorization provided by classes or interfaces. All objects can be identified and differentiated by duck typing. Basically, properties and methods are put in objects on runtime, instead of previously declared in classes; inheritance is obtained by object cloning and dynamic insertion of properties. Thus parent objects act as prototypes for their children.

This allow you to quickly code, once you do structural changes in your source code while you're programming. However, although good for small projects, it can generate unmaintainable applications. It's recommmended that you use prototyping to prototype application modules first and implement an equivalent traditional class-based structure after.

Installation

The recommended way to install this package is through Composer. Create a common composer.json file and run:

$ composer require tassoevan/prototype

Documentation

Basic usage

All prototypes are instances of TassoEvan\Prototype\Prototype class. Properties can be added and removed exactly like the native stdClass. The key difference between Prototype and stdClass is that the last one doesn't handle callable arguments and closures well. You can call closures in a Prototype instance exactly as they are methods.

<?php
use TassoEvan\Prototype\Prototype;

$obj = new Prototype();
$obj->a = function($x) {
	return $x + 2;
};

$obj->a(2); // returns 4

Also, you can use Prototype instances as closures too:

<?php
use TassoEvan\Prototype\Prototype;

$obj = new Prototype(function($x) {
     return $x + 2;
});

$obj(2); // returns 4

Property wrappers

All properties assigned to Prototype instances are wrapped in instances of abstract class TassoEvan\Prototype\Property. It can be done explicitly instantiating these objects or calling static methods from TassoEvan\Prototype\Prototype, implicitly wrapping normal properties by simple assignment though.

Explicitly, instanciating TassoEvan\Prototype\Property:

<?php
use TassoEvan\Prototype\Prototype;
use TassoEvan\Prototype\NormalProperty;

$obj = new Prototype();
$obj->a = new NormalProperty('My value');

echo $obj->a; // outputs 'My value'

Explicitly, via static methods of TassoEvan\Prototype\Prototype:

<?php
use TassoEvan\Prototype\Prototype;

$obj = new Prototype();
$obj->a = Prototype::normal('My value');

echo $obj->a; // outputs 'My value'

Implicitly (TassoEvan\Prototype\NormalProperty only):

<?php
use TassoEvan\Prototype\Prototype;

$obj = new Prototype();
$obj->a = 'My value';

echo $obj->a; // outputs 'My value'

TassoEvan\Prototype\NormalProperty

A normal property can be assigned, evaluated and called (if it is callable) as any variable or object public property in PHP.

<?php
use TassoEvan\Prototype\Prototype;

$obj = new Prototype();
$obj->a = 'My value';

echo $obj->a; // outputs 'My value'

$obj->a = 'My new value';

echo $obj->a; // outputs 'My new value'

TassoEvan\Prototype\ReadOnlyProperty

A read only property can't be overwritten. In strict mode, a exception will be thrown when a new assignment is done.

<?php
use TassoEvan\Prototype\Prototype;

$obj = new Prototype();
$obj->a = Prototype::readOnly('My value'); // non-strict

echo $obj->a; // outputs 'My value'
$obj->a = 'My new value';
echo $obj->a; // outputs 'My value'

$obj->b = Prototype::readOnly('My value', true); // strict

echo $obj->b; // outputs 'My value'
$obj->b = 'My new value'; // a `UnexpectedValueException`

TassoEvan\Prototype\LazyProperty

A lazy property has the ability to be lazy-loaded: at first try to get a value (or call it), a callable named loader is invoked to generate the property value, that will be stored. After loaded, the property behaves like a normal property.

<?php
use TassoEvan\Prototype\Prototype;

$obj = new Prototype();

$obj->db = Prototype::lazy(function() use($myDSNString) {
    // connected only when used
    return new PDO($myDSNString);
});

$obj->db->exec('UPDATE poke_registry SET pokes = pokes+1'); // connects to database and performs a query

TassoEvan\Prototype\ProxyProperty

TassoEvan\Prototype\DynamicProperty

A dynamic property doesn't have a stored value: you should define a getter and a setter callables to offer some value. Can be useful to represent or be a facade to service providers and containers.

<?php
use TassoEvan\Prototype\Prototype;

$obj = new Prototype();

$obj->a = Prototype::dynamic(function() {
        return "foo";
    },
    function($value) {
        echo "Do you want to set {$value} to this property?";
    });

echo $obj->a;           // outputs "foo"
$obj->a = 3;            // outputs "Do you want to set 3 to this property?"

Additional features

• Prototype::closure($callable): transforms any callable in a closure that can be passed to Prototype instances
• Prototype::data(Prototype $obj): creates an array with all data that your prototype stores or generates: that means that Prototype::dynamic() and Prototype::lazy() calls will be performed. This static method was implemented attending the fact that prototypes can't be serialized, once they store closures. Further it can be reviewed.

Contributions

You are free to fork and contribute to this project.