added settings listner

isettings.cpp

@@ -58,6 +58,10 @@ void ISettings::sync() {
 
 void ISettings::setValue(const QString key, const QVariant &value) {
 
+    if (_cache.contains(key) && _cache.value(key) == value) {
+        return;
+    }
+
     _cache[key] = value;
 
     emit valueChanged(key, value);

settingslistner.cpp

@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2018-2021 QuasarApp.
+ * Distributed under the lgplv3 software license, see the accompanying
+ * Everyone is permitted to copy and distribute verbatim copies
+ * of this license document, but changing it is not allowed.
+*/
+
+#include "isettings.h"
+#include "settingslistner.h"
+
+namespace QuasarAppUtils {
+
+SettingsListner::SettingsListner() {
+
+    auto settings = ISettings::instance();
+    if (settings) {
+
+        auto listner = [this](const QString& key, const QVariant& val){
+            this->handleSettingsChanged(key, val);
+        };
+
+        _listnerConnection = QObject::connect(settings,
+                                              &ISettings::valueChanged,
+                                              listner);
+    }
+}
+
+SettingsListner::~SettingsListner() {
+    QObject::disconnect(_listnerConnection);
+}
+
+}

settingslistner.h

@@ -0,0 +1,58 @@
+/*
+ * Copyright (C) 2018-2021 QuasarApp.
+ * Distributed under the lgplv3 software license, see the accompanying
+ * Everyone is permitted to copy and distribute verbatim copies
+ * of this license document, but changing it is not allowed.
+*/
+
+#ifndef SETTINGSLISTNER_H
+#define SETTINGSLISTNER_H
+
+#include <QString>
+#include <QVariant>
+
+
+namespace QuasarAppUtils {
+
+/**
+ * @brief The SettingsListner class is listner of the ISettings global object.
+ * The SettingsListner class is abstrct class and contains only one method for hendling settings changes.
+ *
+ *
+ * ### Example of use :
+ *
+ * @code{cpp}
+ *  class MyClass : protected QuasarAppUtils::SettingsListner {
+ *  protected:
+ *      void handleSettingsChanged(const QString& key, const QVariant& value) override {
+ *
+ *          if (key == "shareName") {
+                setSessinon(static_cast<long long >(rand()) * rand());
+            }
+ *      }
+ *
+ *  };
+ * @endcode
+ * @see ISettings
+ */
+class SettingsListner
+{
+public:
+    SettingsListner();
+    virtual ~SettingsListner();
+
+protected:
+
+    /**
+     * @brief handleSettingsChanged This method will be invoked when settings of application has bean changed.
+     * @param key This is key of a changed settings.
+     * @param value This is a new value of a changed settings.
+     */
+    virtual void handleSettingsChanged(const QString& key,
+                                       const QVariant& value) = 0;
+private:
+    QMetaObject::Connection _listnerConnection;
+};
+
+}
+#endif // SETTINGSLISTNER_H