PHP: Cleanest way to modify multidimensional array?

Question

I've got a Config class in my application, which loads static config settings and parses them into arrays.
As I need to override some elements during runtime, I would need to access the public variable inside the Config-class by doing this; $config->values['onelevel']['twolevel'] = 'changed';

I would like to make a method that is called override that does this for me, but I cant get my head around what would be the best way to do it as my config files may get unknown amount of nested levels in the future.

It would be lovely to do something like $config->onelevel->twolevel = 'changed' and let the __set magic method take care of the nesting, but from what I can tell, it isn't possible.

What would be the best way to do this?

Answer 1

It is possible to do what you want.

This example is largly inspired by Zend_Config and the example given in the PHP docs on the ArrayAccess interface.

edit:
With one minor caveat: you need to call toArray() on data representing an array, to convert it to an array, as the class internally needs to covert array data to an instance of itself, to allow access with the object property operator ->:

Eh, that's not really necessary anymore of course, since it implements ArrayAccess now. ;-)
/edit

class Config
    implements ArrayAccess
{
    protected $_data;

    public function __construct( array $data )
    {
        foreach( $data as $key => $value )
        {
            $this->$key = $value;
        }
    }

    public function __get( $key )
    {
        return $this->offsetGet( $key );
    }

    public function __isset( $key )
    {
        return $this->offsetExists( $key );
    }

    public function __set( $key, $value )
    {
        $this->offsetSet( $key, $value );
    }

    public function __unset( $key )
    {
        $this->offsetUnset( $key );
    }

    public function offsetSet( $offset, $value )
    {
        $value = is_array( $value ) ? new self( $value ) : $value;

        if( is_null( $offset ) )
        {
            $this->_data[] = $value;
        }
        else
        {
            $this->_data[ $offset ] = $value;
        }
    }

    public function offsetExists( $offset )
    {
        return isset( $this->_data[ $offset ] );
    }

    public function offsetUnset( $offset )
    {
        unset( $this->_data[ $offset ] );
    }

    public function offsetGet( $offset )
    {
        return isset( $this->_data[ $offset ] ) ? $this->_data[ $offset ] : null;
    }

    public function toArray()
    {
        $array = array();
        $data = $this->_data;
        foreach( $data as $key => $value )
        {
            if( $value instanceof Config )
            {
                $array[ $key ] = $value->toArray();
            }
            else
            {
                $array[ $key ] = $value;
            }
        }
        return $array;
    }
}

edit 2:
The Config class can even be greatly simplified by extending ArrayObject. As an added benefit, you can cast it to a proper array also.

class Config
    extends ArrayObject
{
    protected $_data;

    public function __construct( array $data )
    {
        parent::__construct( array(), self::ARRAY_AS_PROPS );
        foreach( $data as $key => $value )
        {
            $this->$key = $value;
        }
    }

    public function offsetSet( $offset, $value )
    {
        $value = is_array( $value ) ? new self( $value ) : $value;

        return parent::offsetSet( $offset, $value );
    }
}

Example usage:

$configData = array(
    'some' => array(
        'deeply' => array(
            'nested' => array(
                'array' => array(
                    'some',
                    'data',
                    'here'
                )
            )
        )
    )
);
$config = new Config( $configData );
// casting to real array
var_dump( (array) $config->some->deeply->nested->array );

$config->some->deeply->nested->array = array( 'new', 'awsome', 'data', 'here' );
// Config object, but still accessible as array
var_dump( $config->some->deeply->nested->array[ 0 ] );

$config[ 'some' ][ 'deeply' ][ 'nested' ][ 'array' ] = array( 'yet', 'more', 'new', 'awsome', 'data', 'here' );
var_dump( $config[ 'some' ][ 'deeply' ][ 'nested' ][ 'array' ] );

$config[ 'some' ][ 'deeply' ][ 'nested' ][ 'array' ][] = 'append data';
var_dump( $config[ 'some' ][ 'deeply' ][ 'nested' ][ 'array' ] );

var_dump( isset( $config[ 'some' ][ 'deeply' ][ 'nested' ][ 'array' ] ) );

unset( $config[ 'some' ][ 'deeply' ][ 'nested' ][ 'array' ] );
var_dump( isset( $config[ 'some' ][ 'deeply' ][ 'nested' ][ 'array' ] ) );

// etc...