Release version 1.1.16 - Singleton pattern for settings page

Fixed persistent duplicate settings page rendering by implementing proper
singleton pattern for admin class and caching settings instance.

Fixes:
- Settings page still appearing twice despite v1.1.15 fix
- Multiple instantiation of WC_TPP_Admin class
- Duplicate creation of WC_TPP_Settings instances

Changes:
- Implemented singleton pattern for WC_TPP_Admin class
- Added private static $instance property with get_instance() method
- Made WC_TPP_Admin constructor private
- Added static $settings_instance property to cache settings page
- Modified add_settings_page() to check and reuse cached settings instance
- Changed instantiation from new WC_TPP_Admin() to WC_TPP_Admin::get_instance()

Technical Details:
- Ensures only one WC_TPP_Admin instance exists throughout plugin lifecycle
- Prevents duplicate filter registrations even if woocommerce_get_settings_pages called multiple times
- Settings page object created once and reused on subsequent filter calls
- Follows WordPress/WooCommerce best practices for singleton implementation

Updated Files:
- includes/class-wc-tpp-admin.php (singleton pattern implementation)
- wc-tier-and-package-prices.php (version 1.1.16)
- composer.json (version 1.1.16)
- CHANGELOG.md (v1.1.16 section)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

CHANGELOG.md

@@ -5,6 +5,28 @@ All notable changes to WooCommerce Tier and Package Prices will be documented in
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [1.1.16] - 2025-12-22
+
+### Fixed
+
+- Settings page still rendering twice in WooCommerce backend despite v1.1.15 fix
+- Multiple instantiation of WC_TPP_Admin and WC_TPP_Settings classes
+
+### Changed
+
+- Implemented singleton pattern for WC_TPP_Admin class with `get_instance()` method
+- Made WC_TPP_Admin constructor private to prevent direct instantiation
+- Added static caching of WC_TPP_Settings instance to prevent duplicate creation
+- Changed class instantiation from `new WC_TPP_Admin()` to `WC_TPP_Admin::get_instance()`
+
+### Technical Details
+
+- Added `private static $instance` property to WC_TPP_Admin class
+- Added `private static $settings_instance` property to cache settings page instance
+- Modified `add_settings_page()` to check and reuse cached settings instance
+- Ensures only one instance of each class exists throughout plugin lifecycle
+- Prevents duplicate filter registrations even if called multiple times
+
 ## [1.1.15] - 2025-12-22
 
 ### Fixed

composer.json

@@ -1,7 +1,7 @@
 {
     "name": "magdev/wc-tier-package-prices",
     "description": "WooCommerce plugin for tier pricing and package prices with Twig templates",
-    "version": "1.1.15",
+    "version": "1.1.16",
     "type": "wordpress-plugin",
     "license": "GPL-2.0-or-later",
     "authors": [

includes/class-wc-tpp-admin.php

@@ -10,7 +10,17 @@ if (!defined('ABSPATH')) {
 if (!class_exists('WC_TPP_Admin')) {
     class WC_TPP_Admin {
 
-    public function __construct() {
+    private static $instance = null;
+    private static $settings_instance = null;
+
+    public static function get_instance() {
+        if (null === self::$instance) {
+            self::$instance = new self();
+        }
+        return self::$instance;
+    }
+
+    private function __construct() {
         add_filter('woocommerce_get_settings_pages', array($this, 'add_settings_page'));
         add_action('admin_enqueue_scripts', array($this, 'enqueue_admin_scripts'));
     }
@@ -19,7 +29,10 @@ if (!class_exists('WC_TPP_Admin')) {
      * Add settings page to WooCommerce settings
      */
     public function add_settings_page($settings) {
-        $settings[] = include WC_TPP_PLUGIN_DIR . 'includes/class-wc-tpp-settings.php';
+        if (null === self::$settings_instance) {
+            self::$settings_instance = include WC_TPP_PLUGIN_DIR . 'includes/class-wc-tpp-settings.php';
+        }
+        $settings[] = self::$settings_instance;
         return $settings;
     }
 
@@ -31,5 +44,5 @@ if (!class_exists('WC_TPP_Admin')) {
     }
 }
 
-new WC_TPP_Admin();
+WC_TPP_Admin::get_instance();
 }

wc-tier-and-package-prices.php

@@ -4,7 +4,7 @@
  * Plugin Name: WooCommerce Tier and Package Prices
  * Plugin URI: https://src.bundespruefstelle.ch/magdev/wc-tier-package-prices
  * Description: Add tier pricing and package prices to WooCommerce products with configurable quantities at fixed prices
- * Version: 1.1.15
+ * Version: 1.1.16
  * Author: Marco Graetsch
  * Author URI: https://src.bundespruefstelle.ch/magdev
  * Text Domain: wc-tier-package-prices
@@ -23,7 +23,7 @@ if (!defined('ABSPATH')) {
 
 // Define plugin constants
 if (!defined('WC_TPP_VERSION')) {
-    define('WC_TPP_VERSION', '1.1.15');
+    define('WC_TPP_VERSION', '1.1.16');
 }
 if (!defined('WC_TPP_PLUGIN_DIR')) {
     define('WC_TPP_PLUGIN_DIR', plugin_dir_path(__FILE__));