CakePHP dynamic database config

database.php

<?php
/**
 * This is core configuration file.
 *
 * Use it to configure core behaviour ofCake.
 *
 * PHP versions 4 and 5
 *
 * CakePHP(tm) : Rapid Development Framework (http://cakephp.org)
 * Copyright 2005-2010, Cake Software Foundation, Inc. (http://cakefoundation.org)
 *
 * Licensed under The MIT License
 * Redistributions of files must retain the above copyright notice.
 *
 * @copyright     Copyright 2005-2010, Cake Software Foundation, Inc. (http://cakefoundation.org)
 * @link          http://cakephp.org CakePHP(tm) Project
 * @package       cake
 * @subpackage    cake.app.config
 * @since         CakePHP(tm) v 0.2.9
 * @license       MIT License (http://www.opensource.org/licenses/mit-license.php)
 */
/**
 * In this file you set up your database connection details.
 *
 * @package       cake
 * @subpackage    cake.config
 */
/**
 * Database configuration class.
 * You can specify multiple configurations for production, development and testing.
 *
 * driver => The name of a supported driver; valid options are as follows:
 *              mysql           - MySQL 4 & 5,
 *              mysqli          - MySQL 4 & 5 Improved Interface (PHP5 only),
 *              sqlite          - SQLite (PHP5 only),
 *              postgres        - PostgreSQL 7 and higher,
 *              mssql           - Microsoft SQL Server 2000 and higher,
 *              db2                     - IBM DB2, Cloudscape, and Apache Derby (http://php.net/ibm-db2)
 *              oracle          - Oracle 8 and higher
 *              firebird        - Firebird/Interbase
 *              sybase          - Sybase ASE
 *              adodb-[drivername]      - ADOdb interface wrapper (see below),
 *              odbc            - ODBC DBO driver
 *
 * You can add custom database drivers (or override existing drivers) by adding the
 * appropriate file to app/models/datasources/dbo.  Drivers should be named 'dbo_x.php',
 * where 'x' is the name of the database.
 *
 * persistent => true / false
 * Determines whether or not the database should use a persistent connection
 *
 * connect =>
 * ADOdb set the connect to one of these
 *      (http://phplens.com/adodb/supported.databases.html) and
 *      append it '|p' for persistent connection. (mssql|p for example, or just mssql for not persistent)
 * For all other databases, this setting is deprecated.
 *
 * host =>
 * the host you connect to the database.  To add a socket or port number, use 'port' => #
 *
 * prefix =>
 * Uses the given prefix for all the tables in this database.  This setting can be overridden
 * on a per-table basis with the Model::$tablePrefix property.
 *
 * schema =>
 * For Postgres and DB2, specifies which schema you would like to use the tables in. Postgres defaults to
 * 'public', DB2 defaults to empty.
 *
 * encoding =>
 * For MySQL, MySQLi, Postgres and DB2, specifies the character encoding to use when connecting to the
 * database.  Uses database default.
 *
 */
class DATABASE_CONFIG {

        var $default = array(
                'driver' => 'mysql',
                'persistent' => false,                
                'login' => '<username>',
                'password' => '<password>',
                'database' => '<db>',
                'prefix' => '',
        );

        var $maint = array(
                'driver' => 'mysql',
                'persistent' => false,                
                'login' => '<username>',
                'password' => '<password>',
                'database' => '<db>',
                'prefix' => '',
        );

        function __construct ()
        {
            //set this in your webserver config
            //i.e. in apache SetEnv DATABASE_HOST "db1.domain.com"
            if(isset($_SERVER['DATABASE_HOST'])){
                    $this->default['host'] = $_SERVER['DATABASE_HOST'];
                    $this->maint['host'] = $_SERVER['DATABASE_HOST'];
            }
            else
            {
                $this->default['host'] = 'localhost';
                $this->maint['host'] = 'localhost';
            }
        }
}

I use this in a scenario where on a staging hostI have access to the db directly and thus define the DATBASE_HOST as the hostname of the database server, but from a remote machine I am not able to connect to the database via tcp port 3306. So on that system I use ssh and map localhost 3306 to the remote server 3306 and change my DATABASE_HOST to localhost on my local development webserver.