private function constants() {

		// Place your custom code (actions/filters) in a file called
		// '/plugins/bp-custom.php' and it will be loaded before anything else.
		if ( file_exists( WP_PLUGIN_DIR . '/bp-custom.php' ) ) {
			require( WP_PLUGIN_DIR . '/bp-custom.php' );
		}

		// Path and URL.
		if ( ! defined( 'BP_PLUGIN_DIR' ) ) {
			define( 'BP_PLUGIN_DIR', plugin_dir_path( __FILE__ ) );
		}

		if ( ! defined( 'BP_PLUGIN_URL' ) ) {
			define( 'BP_PLUGIN_URL', plugin_dir_url( __FILE__ ) );
		}

		// Legacy forum constant - supported for compatibility with bbPress 2.
		if ( ! defined( 'BP_FORUMS_PARENT_FORUM_ID' ) ) {
			define( 'BP_FORUMS_PARENT_FORUM_ID', 1 );
		}

		// Legacy forum constant - supported for compatibility with bbPress 2.
		if ( ! defined( 'BP_FORUMS_SLUG' ) ) {
			define( 'BP_FORUMS_SLUG', 'forums' );
		}

		// Only applicable to those running trunk.
		if ( ! defined( 'BP_SOURCE_SUBDIRECTORY' ) ) {
			define( 'BP_SOURCE_SUBDIRECTORY', '' );
		}

		// Define on which blog ID BuddyPress should run.
		if ( ! defined( 'BP_ROOT_BLOG' ) ) {

			// Default to use current blog ID.
			// Fulfills non-network installs and BP_ENABLE_MULTIBLOG installs.
			$root_blog_id = get_current_blog_id();

			// Multisite check.
			if ( is_multisite() ) {

				// Multiblog isn't enabled.
				if ( ! defined( 'BP_ENABLE_MULTIBLOG' ) || ( defined( 'BP_ENABLE_MULTIBLOG' ) && (int) constant( 'BP_ENABLE_MULTIBLOG' ) === 0 ) ) {
					// Check to see if BP is network-activated
					// We're not using is_plugin_active_for_network() b/c you need to include the
					// /wp-admin/includes/plugin.php file in order to use that function.

					// Get network-activated plugins.
					$plugins = get_site_option( 'active_sitewide_plugins');

					// Basename.
					$basename = basename( constant( 'BP_PLUGIN_DIR' ) ) . '/bp-loader.php';

					// Plugin is network-activated; use main site ID instead.
					if ( isset( $plugins[ $basename ] ) ) {
						$current_site = get_current_site();
						$root_blog_id = $current_site->blog_id;
					}
				}

			}

			define( 'BP_ROOT_BLOG', $root_blog_id );
		}

		// The search slug has to be defined nice and early because of the way
		// search requests are loaded.
		//
		// @todo Make this better.
		if ( ! defined( 'BP_SEARCH_SLUG' ) ) {
			define( 'BP_SEARCH_SLUG', 'search' );
		}
	}