[js.php] A JavaScript Object Like PHP Class

PHP 5.3 introduces the Closure class which is really useful and more powerful than good old lambdas via create_function.
These are main limits of Closure class:

you cannot serialize a Closure instance (and json_encode does not solve the problem at all)

you cannot inject scopes via $this unless the closure comes from a class method

While with an emulated prototype style class, something I tried months ago as well, the first point could not be a problem, to solve the second one is quite inevitable to use a Python like variable as first argument, called $self, to make the Closure both portable and re-adaptable.

JSObject :: JavaScript Object Like PHP Class


/** js.php basic JSObject implementation
 * @author  Andrea Giammarchi
 * @blog    WebReflection.blogspot.com
 * @license Mit Style License
 */
class JSObject implements ArrayAccess {

    // public static prototype
    static  public  $prototype;

    // ArrayAccess Interface
    public  function    offsetExists($index){return  isSet($this->$index);}
    public  function    offsetGet($index){return  $this->$index;}
    public  function    offsetSet($index, $value){$this->$index = $value;}
    public  function    offsetUnset($index){unset($this->$index);}

    // Invoked lambdas via $this or self::$prototype
    public  function    __call($index, array $arguments){

        // inject $this as first argument
        array_unshift($arguments, $this);

        // invoke the callback
        return  call_user_func_array(
        
            // if it has been assigned to the object itself
            isset($this->$index) ?

                // it has priority
                $this->$index :
                
                // otherwise invoke from self::$prototype
                self::$prototype->$index
            ,
            $arguments
        );
    }

    // JS like behavior, ready for extends
    public  function    __toString(){
        return  '[object '.get_class($this).']';
        // e.g. [object JSObject]
    }

    // Relevant Global Object implementations
    public  function    getPrototypeOf(){
        return  get_class($this);
    }
    public  function    hasOwnProperty($index){
        return  isset($this->$index);
    }
    public  function    isPrototypeOf(/* string */ $class){
        return  $this instanceof $class;
    }
    public  function    toSource(){
        // we could implement __sleep and __wakeup
        // to avoid closure serialization (not possible yet)
        return  serialize($this);
    }
    public  function    toString(){
        return  $this->__toString();
    }


    // not standard method, anyway useful
    public  function    toJSONString(){
        // we could parse properties in a foreach
        // to filter meaningless closures, if any
        return  json_encode($this);
    }
}

// the global prototype is a JSObject too
JSObject::$prototype = new JSObject;

// JSObject factory: e.g. $myobj = JSObject(); // rather than new JSObject;
function JSObject(){
    return  new JSObject();
}

Above class uses an interface from the great SPL, an in-core extension present since PHP 5.1
The rest is theoretically compatible with old style lambdas, static functions, or new Closure instances. Here we go with some example:


// we can assigns prototypes everywhere ...
JSObject::$prototype->getName = function($self){
    return  $self->name;
};

$o = JSObject();

// ... even after JSObject instances creation
JSObject::$prototype->writeAge = function($self){
    echo $self->getName().' is '.$self->age.' years old.';
};

// assign properties
$o->name    = 'Andrea';
$o->age     = 30;

// test some JS method
echo    $o->toJSONString();
// {"name":"Andrea","age":30}

echo    $o;
// [object JSObject]

echo    $o->toSource();
// O:8:"JSObject":2:{s:4:"name";s:6:"Andrea";s:3:"age";i:30;}

// or tests runtime methods
$o->writeAge();
// Andrea is 30 years old.

// we can assign a custom method runtime
$o->getSurname = function($self){
    return  'Giammarchi';
};

// custom methods have priority over prototype
$o->getName = function($self){
    return  $self->name.' '.$self->getSurname();
};

$o->writeAge();
// Andrea Giammarchi is 30 years old.

Is it cool? And more is coming for backward compatibility:


// prototype via function name resolution
JSObject::$prototype->getName = 'JSObject_getName';

// the function with a prefix to avoid conflicts
function JSObject_getName($self){
    return  $self->name;
}

// a simple test case
$o = JSObject();
$o->name    = 'Andrea';

echo    $o->getName();
// Andrea

And obviously we can do the same with create_function:


// prototype via lambda
JSObject::$prototype->getName = create_function('$self','
    return  $self->name;
');

Conclusion

Via SPL, closures, and some convenient trick, we could completely change the code style of PHP. Performances are always a priority, in any case, but with a couple of good practices, some discarded or "language useless" piece of ECMAScript, we could use JS style as low level structure for more Object Oriented frameworks or completely different ways to code.

What's next?

It is ages that I am waiting for a stable PHP 5.3 plus PECL extensions (in particular the php_operator to add operator overloads) to be able to create a JavaScript version of PHP. I have already created similar classes and my vision is a one2one JavaScript style framework created entirely via PHP. Craziness? Non-sense? Dunno, just try to imagine a Jaxer like behavior in every host with "just" PHP support ... is it a cool idea? Well, please contact me if you are interested ;)

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