Replaced hardcoded directory names with constants

Implementation of these constants in place of the hardcoded directory
names is incomplete

lib/wp-librarian.class.php

@@ -7,6 +7,18 @@
  * @todo Define custom post type/taxonomy names as class constants
  */
 class WP_Librarian {
+	/**
+	 * Paths to plugin's subdirectories
+	 * USe these rather than hard-coding subdirectory names
+	 */
+	const SCRIPT_DIR        = 'scripts';
+	const STYLE_DIR         = 'styles';
+	const MINIFIED_DIR      = 'data';
+	const CLASS_DIR         = 'lib';
+	const HELPER_DIR        = 'helpers';
+	const TEMPLATE_DIR      = 'templates';
+	const ADMIN_TEMPLATE_DIR= 'admin-templates';
+
 	/**
 	 * Path to plugin folder, without trailing slash
 	 * @var string
@@ -107,15 +119,15 @@ private function registerHooks() {
 	 * @param   string  $helper Name of helper file, excluding .class.php
 	 */
 	public function loadHelper($helper) {
-		require_once($this->plugin_path . '/helpers/' . $helper . '.class.php');
+		require_once($this->plugin_path . '/' . self::HELPER_DIR . '/' . $helper . '.class.php');
 	}
 
 	/**
 	 * Loads library class from /lib directory
 	 * @param   string  $helper Name of library to be loaded, excluding .class.php
 	 */
 	public function loadClass($library) {
-		require_once($this->plugin_path . '/lib/' . $library . '.class.php');
+		require_once($this->plugin_path . '/' . self::CLASS_DIR . '/' . $library . '.class.php');
 	}
 
 	/**
@@ -132,7 +144,7 @@ public function loadObjectClasses() {
 	 * @param   array   $params OPTIONAL Associative array of parameters for the template
 	 */
 	public function loadAdminTemplate($name, Array $params = array()) {
-		require_once($this->plugin_path . '/admin-templates/' . $name . '.php');
+		require_once($this->plugin_path . '/' . self::ADMIN_TEMPLATE_DIR . '/' . $name . '.php');
 	}
 
 	/**
@@ -1191,9 +1203,9 @@ public function getUserRoles() {
 	public function getStyleUrl($name) {
 		// Loads minified assets in production. Regular for dev/debugging
 		if ((defined('SCRIPT_DEBUG') && SCRIPT_DEBUG) || WP_LIB_DEBUG_MODE) {
-			return $this->plugin_url . '/styles/' . $name . '.css';
+			return $this->plugin_url . '/' . self::STYLE_DIR . '/' . $name . '.css';
 		} else {
-			return $this->plugin_url . '/data/' . $name . '.min.css';
+			return $this->plugin_url . '/' . self::MINIFIED_DIR . '/' . $name . '.min.css';
 		}
 	}
 
@@ -1205,9 +1217,9 @@ public function getStyleUrl($name) {
 	public function getScriptUrl($name) {
 		// Loads minified assets in production. Regular for dev/debugging
 		if ((defined('SCRIPT_DEBUG') && SCRIPT_DEBUG) || WP_LIB_DEBUG_MODE) {
-			return $this->plugin_url . '/scripts/' . $name . '.js';
+			return $this->plugin_url . '/' . self::SCRIPT_DIR . '/' . $name . '.js';
 		} else {
-			return $this->plugin_url . '/data/' . $name . '.min.js';
+			return $this->plugin_url . '/' . self::MINIFIED_DIR . '/' . $name . '.min.js';
 		}
 	}
 
@@ -1217,7 +1229,7 @@ public function getScriptUrl($name) {
 	 * @return  string          Full file path e.g. '.../templates/archive-wp_lib_items.php'
 	 */
 	public function getTemplateDir($name) {
-		return $this->plugin_path . '/templates/' . $name . '.php';
+		return $this->plugin_path . '/' . self::TEMPLATE_DIR . '/' . $name . '.php';
 	}
 
 	/*