Serialization support

[mrferos]

Funky test because serializing an object with protected/private properties outputs zero-width binary characters. There are 1) hard to copy/paste and 2) result in the file being recognized as binary by GitHub resulting in no longer being able to do diffs easily. Below is an example:

<?php
require_once __DIR__ . '/vendor/autoload.php';

$map = new \Zumba\Swivel\Map(array(
    'feature.test' => array(1,2,3)
));



$d =  serialize($map);
echo $d, "\n";
echo md5($d), "\n";
$d = 'O:16:"Zumba\Swivel\Map":1:{s:6:"*map";a:1:{s:12:"feature.test";i:7;}}';
echo $d, "\n";
echo md5($d), "\n";

[mglinski]

Implementing __set_state(array) here is still valid, it just does not cover the same cases as __sleep(). You were just trying to use __set_state() as __sleep(). The following code should work for the __set_state() use cases:

public static function __set_state($map_data) // As of PHP 5.1.0
{
    $map = new Map($map_data['map']);
    return $map;
}

[mrferos]

@mglinski assuming $map_data['map'] contains unprocessed values that works, but var_export will echo out the already processed value of the map property. __set_state was created because of var_export and in a normal use case, it will produce an export calling __set_state on the logger. The logger interface does not implement __set_state so we can't guarantee this would work. The original implementation attempted to solve this by removing it but given the intended use case (#2), it looked like using __sleep/__wakeup more cleanly addressed it.

[mglinski]

I will implement var_export() support in a new PR, should be up shortly.

Added in #21