PHP static as virtual self, what else for parent?

I find the static keyword in PHP 5.3 absolutely useful, but I instantly felt into a dilemma: what about parent?

With static it is possible to refer to a generic class static property, without referring the class where the method has been declared.
Here there is a simple example:

class Numbers {
    public static $value = 0;
    public static function getValue(){
        return static::$value;
    }
}

class One extends Number {
    public static $value = 1;
}

class Two extends Number {
    public static $value = 2;
}

$one = new One;
$two = new Two;
$one->getValue(); // 1
$two->getValue(); // 2

Above example shows how static behaves when an instance calls a method which uses static keyword.
Whatever subclass it is, we will always obtain the defined value (if any, otherwise the inherited one) as expected.

But what about parent behavior?

If we use parent inside a method it is like using self, the parent keyword will always refers to the parent class, if any, of the method which contains the parent keyword. If we add a function like this in the Numbers class:

    public static function getParentValue(){
        return parent::$value;
    }

every subclass wont be able to show the Numbers $value and an error will be generated instead.

To obtain the desired result we have to use the ReflectionClass:

    // class Numbers ...
    public static function getParentValue(){
        $class = new ReflectionClass($this);
        return $class->getParentClass()->getStaticPropertyValue('$value');
    }

Above code is much slower than parent::$value because of the instance creation plus its method call for each ReflectionClass instance ($this plus the one returned by getParentClass)

Now, the question is: is it truly necessary? Will we have other ways to retrieve a "static parent" from a method?

32 bytes, ehr ... 9, ehr ... 7!!! to know if your browser is IE

Update another clever trick from comments, which I will explain later:

if(!+"\v1") // true only in IE
if("\v"=="v")// true only in IE
try{IE=window=!1}catch(e){IE=!0}

it works, doesn't it?

The reason is simple, if we consider "\v" as a vertical space, browsers interpreter that check in this way:

!(+
1
)

where "not one" is always false, considering that 0 is always casted as false, and every other number is casted as true.

Internet Explorer will ignore the vertical space, trying to cast a "v" character into a number, thanks to the sign (plus or minus, it does not matter)

// How IE interpreters the code
!(+"v")

// where 
isNaN(+"v") === true
// and where NaN is implicitly casted as false

About conditional comments

I read a lot of comments in both Ajaxian and other places ... well, guys, this is a trick as conditional comment is.
The day IE will interpret correctly the "\v" character, Opera or some other browser could implement conditional comments as well.
That's my simple point of view:
conditional comments could be stripped out from minifiers (not MyMin) and make code difficult do understand or maintain while this 7 bytes trick is portable, minifier/packer safe, and extremely easy to maintain (the day IE will be able to return a false, we'll have solved almost every cross browser problem thanks to JS2 but just in case, all we need to do, will be a simple replace with the isIE.Next trick)


Note this trick is library/hack proof. If you think that execScript check is enough, for example, consider this: top["execScript"]=null and/or libraries that implements execScript for other browsers.

png to gif transformation - an excellent free solution via PHP GD2

Why we still need png to gif in our web pages

There a couple of valid plugins for different libraries able to manage "silently" png transparency in order to fix those browsers (cough: IE6) that are still used, for god knows which reason, but not able to understand properly the alpha channel. The problem is that these plugins cause overhead in our pages and for each png images, which is nearly a non-sense since these plugins fix old browsers whose performances have never been brilliant!
Especially for modern GUIs, where little icons are widely used, these plugins could make the application incredibly slow.
If we could choose old good GIF instead of png, 'till the end of those browsers, the problem will not exist and performances will be acceptable.

PNG 2 GIF, simple? ... not, really!

First of all a couple of search via Google brought me in "free but you have to pay anyway" applications through some open source, simple, but not that nice, program language solution, incompatible with modern interpreters or not able to produce a good quality result.
The problem is basically this one: alpha channel is something amazing, but it changes border colors if we are putting the png over a bright background rather than a dark one.
For this reason it is really difficult to obtain a valid GIF copy of the original PNG feel using common transformers, since the main difference is given by our cool theme that can be bright or dark.
Thanks to PHP and its distributed GD2 library, I have been able to create a good compromise between pixelated borders and our chose theme.

png2gif, the php/gd2 way

function png2gif($pngs, $background = array(255, 255, 255), $dest = 'gif'){
    // by WebReflection
    foreach($pngs as $png){
        $size = getimagesize($png);
        $img = imagecreatefrompng($png);
        $image = imagecreatetruecolor($width = $size[0], $height = $size[1]);
        imagefill($image, 0, 0, $bgcolor = imagecolorallocate($image, $background[0], $background[1], $background[2]));
        imagecopyresampled($image, $img, 0, 0, 0, 0, $width, $height, $width, $height);
        imagecolortransparent($image, $bgcolor);
        imagegif($image, str_ireplace('.png', '.gif', $dest.DIRECTORY_SEPARATOR.basename($png)), 100);
        imagedestroy($image);
    }
}

// example
png2gif(glob("icons/*.png"));

That's it, you copy and paste an entire directory into, for example, an icons folder, and you call the function passing the list of files contained in that directory.
Parameters are the file list itself, the background color, and finally the destination folder to put transformed png into gif, by default the dir "gif".
The main difference between this function and every other method I found, is that borders are gracefully adapted to your main theme, by default a bright one with white background.
In this way you can choose how borders should be readapted instead of black borders for alpha problems, or cutted one. Even circle icons result are, in my opinion, brilliant!
The array should contain R,G,B integer values, from 0 to 255, where array(0,0,0) is black and array(255,255,255) is white, the default background theme.

You can try this function to convert most common icons theme, and please tell me if the result was not good enough ;-)

P.S. for PHP maniacas, the imagecopyresampled gd2 function has been the only one able to merge properly the png into chose background color ... I don't want to tell you how long did it take to find this kind of solution (passing via pixel by pixel color allocation ... omg!)