A simple struct class for PHP.

struct.php

<?php

abstract class Struct implements \ArrayAccess
{
    function __construct($properties = array())
    {
        $this->init();

        foreach ($properties as $property => $value) {
            $this->$property = $value;
        }
    }

    function init()
    {}

    function offsetGet($offset)
    {
        return $this->$offset;
    }

    function offsetSet($offset, $value)
    {
        $this->$offset = $value;
    }

    function offsetExists($offset)
    {
        return isset($this->$offset);
    }

    function offsetUnset($offset)
    {
        unset($this->$offset);
    }

    final function __get($property)
    {
        throw new \RuntimeException(sprintf('Undefined field "%s"', $property));
    }

    final function __set($property, $value)
    {
        throw new \RuntimeException(sprintf('Undefined field "%s"', $property));
    }
}

# Defining structs works like defining a class, and the fields are its public members.
class Pathinfo extends Struct
{
    var $dirname;
    var $basename;
    var $extension;
    var $filename;

    # Structs can also implement an "init" method, which can initialize
    # fields with complex values (like objects)
    #
    # function init() {
    # }
}

# Structs feature a default constructor which takes an array
# and assigns the keys as properties.
$i = new Pathinfo([
    'dirname' => '/foo', 'basename' => 'bar.php', 'extension' => 'php'
]);

# Fields can be accessed either via brackets or as object member.
printf("Basename: %s\n", $i["basename"]);
printf("Dirname: %s\n", $i->dirname);

# Trying to access undefined fields causes an Exception
try {
    $i['foo'];
} catch (\RuntimeException $e) {
    echo $e->getMessage(), "\n";
}

Please tell me in comments if this would be sufficient as Struct class for PHP. If yes then I will work on releasing this as a small library.

Went looking on Packagist for this today, so I suppose my answer is "yes, this would be sufficient".