How do you change the theme location?

Question

To change the upload directory I have to do this:

define ( "upload", "<new upload location>" );

How can you change the themes location? I like to create a folder themes in the root directory.

Answer 1

You can register additional directory or directories with themes by using register_theme_directory() function, that accepts filesystem path to folder.

Note that this isn't typical and even while core handles it mostly fine, third party code in themes and plugins might not.

Answer 2

You have to change the path and the URL to make sure themes work. I am using the following MU-Plugin in one of my local setups:

<?php
/* Plugin Name: Local Theme Roots */

if ( 'single.wp' === $_SERVER['HTTP_HOST'] )
    return;

add_filter( 'theme_root_uri', 't5_switch_theme_root' );
add_filter( 'theme_root',     't5_switch_theme_root' );

/**
 * Create a custom theme directory.
 *
 * @wp-hook theme_root
 * @wp-hook theme_root_uri
 * @author  Thomas Scholz, http://toscho.de
 * @param   string $in URL or path
 * @return  string
 */
function t5_switch_theme_root( $in )
{
    // local multi-sites end with 'mu.wp'. Example: t5.mu.wp.
    if ( 0 !== stripos( strrev( $_SERVER['HTTP_HOST'] ), 'pw.um' ) )
    {
        return $in;
    }


    if ( 'theme_root_uri' === current_filter() )
    {
        return "http://themes.wp";
    }

    // If we made it so far we are in the 'theme_root' filter.
    $new_root = dirname( dirname( __DIR__ ) ) . '/wp-themes';
    register_theme_directory( $new_root );
    return $new_root;
}

Be aware automatic theme upgrades will not work now due to a bug in the upgrader. I have fixed that and submitted a patch, but until 3.6 comes out you have to run upgrades separately.