finished implementation of XmlAppSettingsProvider,

added description to IAppSettingsProvider methods,
added loading and saving to settings on app startup and exit,
cleaned up ShellViewModel

Common/AppSettings/IAppSettingsProvider.cs

@@ -12,18 +12,44 @@ public interface IAppSettingsProvider
     /// <summary>
     /// Retrieves the app settings from the persistant location and loads them into memory.
     /// Loading settings will override the currently stored settings in the memory.
+    /// If loading happens and there were already settings in the memory, a <see cref="LogWorthyEvent"/> is generated.
     /// </summary>
     void Load();
 
     /// <summary>
     /// Saves the app settings to the persistant location.
+    /// If the saving does not work, logs the exception as a <see cref="LogWorthyEvent"/> but does not throw an exception.
+    /// Rationale: A User is happier if the app is useable and does not remember settings than if the app always throws an exception on startup.
     /// </summary>
     void Save();
 
-
+    /// <summary>
+    /// Creates a new setting or overwrites the value of an existing setting in the memory (not persistent location). Settings are identified by key.
+    /// Informs about issues using the <see cref="LogWorthyEvent"/>.
+    /// </summary>
+    /// <param name="key">key of the setting, must not be empty or null</param>
+    /// <param name="value">value of the setting, must not be empty or null</param>
+    /// <returns>true if the setting is successfully written or overwritten</returns>
     bool WriteSetting(string key, string value);
 
+    /// <summary>
+    /// Tries to read a setting from the memory (not persistent location). Settings are identified by key.
+    /// Informs about issues using the <see cref="LogWorthyEvent"/>.
+    /// If no setting with the given <paramref name="key"/> is found, the <paramref name="value"/> is set to <see cref="String.Empty"/>.
+    /// </summary>
+    /// <param name="key">key of the setting, must not be empty or null</param>
+    /// <param name="value">the found value or an empty string if no setting is found</param>
+    /// <returns>true when the setting exists and could be read successfully</returns>
     bool TryReadSetting(string key, out string value);
 
+    /// <summary>
+    /// Tries to read a setting from the memory (not persistent location). Settings are identified by key.
+    /// Informs about issues using the <see cref="LogWorthyEvent"/>.
+    /// If no setting with the given <paramref name="key"/> is found, the setting is created with the given <paramref name="defaultValue"/>. <paramref name="value"/> is also set to <paramref name="defaultValue"/>.
+    /// </summary>
+    /// <param name="key">key of the setting, must not be empty or null</param>
+    /// <param name="value">the found value or an empty string if no setting is found</param>
+    /// <param name="defaultValue">the default value to initialize the setting with if it does not exist yet. must not be empty or null</param>
+    /// <returns>true when the setting could be read or was created successfully</returns>
     bool TryReadSettingOrAddDefault(string key, out string value, string defaultValue);
 }

Common/AppSettings/XmlAppSettingsProvider.cs

@@ -14,12 +14,17 @@ public class XmlAppSettingsProvider : IAppSettingsProvider
     public XmlAppSettingsProvider(string settingsFilePath)
     {
         // check for file path validity
-        // TODO create file if it does not exist yet
         if (String.IsNullOrEmpty(settingsFilePath)) { throw new ArgumentNullException(nameof(settingsFilePath)); }
 
         this.settingsFilePath = settingsFilePath;
         this.settings = new List<AppSetting>();
         this.serializer = new XmlSerializer(typeof(List<AppSetting>));
+
+        // create file if it does not exist yet
+        if (File.Exists(settingsFilePath) == false)
+        {
+            this.Save();
+        }
     }
 
     public void Load()
@@ -35,24 +40,33 @@ public class XmlAppSettingsProvider : IAppSettingsProvider
             if(this.settings.Count > 0) 
             {
                 this.LogWorthyEvent?.Invoke(this, new LogEntry(level: LogLevel.Warn, category: nameof(XmlAppSettingsProvider),
-                    message: $"'{nameof(Load)}'() deserialization overwrote previously loaded settings."));
+                    message: $"'{nameof(Load)}()' deserialization overwrote previously loaded settings."));
             }
             this.settings = (List<AppSetting>)deserializedObj;
         }
         else
         {
             this.LogWorthyEvent?.Invoke(this, new LogEntry(level: LogLevel.Warn, category: nameof(XmlAppSettingsProvider),
-                    message: $"'{nameof(Load)}'() deserialization resulted in null object. Did not change loaded settings."));
+                message: $"'{nameof(Load)}()' deserialization resulted in null object. Did not change loaded settings."));
         }
     }
 
     public void Save()
     {
-        // TODO write log entries for when something goes wrong
+        // if saving fails, just log the exception. user is happier if the app is useable but does not remember settings
+        try
+        {
+            // create file and serialize data
             TextWriter writer = new StreamWriter(this.settingsFilePath);
             this.serializer.Serialize(writer, this.settings);
             writer.Close();
         }
+        catch (Exception ex)
+        {
+            this.LogWorthyEvent?.Invoke(this, new LogEntry(){ LogLevel = LogLevel.Error, Category = nameof(XmlAppSettingsProvider),
+                Message = $"'{nameof(Save)}()' failed to create file or serialize data.", Exception = ex });
+        }
+    }
 
 
 
@@ -69,7 +83,7 @@ public class XmlAppSettingsProvider : IAppSettingsProvider
         if(foundSettings.Count > 1)
         {
             this.LogWorthyEvent?.Invoke(this, new LogEntry(level: LogLevel.Error, category: nameof(XmlAppSettingsProvider),
-                message: $"'{nameof(WriteSetting)}'() cancelled because {foundSettings.Count} settings with the key '{key}' were found. Expected none or exactly one."));
+                message: $"'{nameof(WriteSetting)}()' cancelled because {foundSettings.Count} settings with the key '{key}' were found. Expected none or exactly one."));
 
             return false;  // cancel
         }
@@ -82,7 +96,7 @@ public class XmlAppSettingsProvider : IAppSettingsProvider
         else if(foundSettings.Count == 0)
         {
             this.LogWorthyEvent?.Invoke(this, new LogEntry(level: LogLevel.Info, category: nameof(XmlAppSettingsProvider),
-                message: $"'{nameof(WriteSetting)}'() initialized new setting with key '{key}' and value '{value}'."));
+                message: $"'{nameof(WriteSetting)}()' initialized new setting with key '{key}' and value '{value}'."));
         }
 
         // add new setting
@@ -102,7 +116,7 @@ public class XmlAppSettingsProvider : IAppSettingsProvider
         if (foundSettings.Count > 1)
         {
             this.LogWorthyEvent?.Invoke(this, new LogEntry(level: LogLevel.Error, category: nameof(XmlAppSettingsProvider),
-                message: $"'{nameof(TryReadSetting)}'() did find {foundSettings.Count} settings with the key '{key}'. Expected only one."));
+                message: $"'{nameof(TryReadSetting)}()' did find {foundSettings.Count} settings with the key '{key}'. Expected only one."));
 
             value = string.Empty;
             return false;
@@ -112,7 +126,7 @@ public class XmlAppSettingsProvider : IAppSettingsProvider
         if (foundSettings.Count == 0)
         {
             this.LogWorthyEvent?.Invoke(this, new LogEntry(level: LogLevel.Error, category: nameof(XmlAppSettingsProvider),
-                message: $"'{nameof(TryReadSetting)}'() did not find a setting with the key '{key}'."));
+                message: $"'{nameof(TryReadSetting)}()' did not find a setting with the key '{key}'."));
 
             value = string.Empty;
             return false;
@@ -128,11 +142,10 @@ public class XmlAppSettingsProvider : IAppSettingsProvider
         else
         {
             this.LogWorthyEvent?.Invoke(this, new LogEntry(level: LogLevel.Warn, category: nameof(XmlAppSettingsProvider),
-                message: $"'{nameof(TryReadSetting)}'() value of retrieved setting with key '{key}' was null. Returned empty string instead."));
+                message: $"'{nameof(TryReadSetting)}()' value of retrieved setting with key '{key}' was null. Returned empty string instead."));
 
             value = string.Empty;
         }
-
         return true;
     }
 
@@ -149,7 +162,7 @@ public class XmlAppSettingsProvider : IAppSettingsProvider
         if (foundSettings.Count > 1)
         {
             this.LogWorthyEvent?.Invoke(this, new LogEntry(level: LogLevel.Error, category: nameof(XmlAppSettingsProvider),
-                message: $"'{nameof(TryReadSettingOrAddDefault)}'() did find {foundSettings.Count} settings with the key '{key}'. Expected only one."));
+                message: $"'{nameof(TryReadSettingOrAddDefault)}()' did find {foundSettings.Count} settings with the key '{key}'. Expected only one."));
 
             value = string.Empty;
             return false;
@@ -159,11 +172,10 @@ public class XmlAppSettingsProvider : IAppSettingsProvider
         if (foundSettings.Count == 0)
         {
             this.LogWorthyEvent?.Invoke(this, new LogEntry(level: LogLevel.Info, category: nameof(XmlAppSettingsProvider),
-                message: $"'{nameof(TryReadSettingOrAddDefault)}'() did not find a setting with the key '{key}'. Adding setting with value '{defaultValue}'."));
+                message: $"'{nameof(TryReadSettingOrAddDefault)}()' did not find a setting with the key '{key}'. Adding setting with value '{defaultValue}'."));
 
-            this.WriteSetting(key, defaultValue);
             value = defaultValue;
-            return true;
+            return this.WriteSetting(key, defaultValue);
         }
 
         // extract correct setting when found exactly one
@@ -176,7 +188,7 @@ public class XmlAppSettingsProvider : IAppSettingsProvider
         else
         {
             this.LogWorthyEvent?.Invoke(this, new LogEntry(level: LogLevel.Warn, category: nameof(XmlAppSettingsProvider),
-                message: $"'{nameof(TryReadSetting)}'() value of retrieved setting with key '{key}' was null. Returned empty string instead."));
+                message: $"'{nameof(TryReadSetting)}()' value of retrieved setting with key '{key}' was null. Returned empty string instead."));
 
             value = string.Empty;
         }

MultiTerm.Core/ViewModel/ShellViewModel.cs

@@ -14,21 +14,18 @@ public partial class ShellViewModel : ObservableObject
     private const string defaultReceiveNewlineSeparatorAppSettingsKey = "DefaultReceiveNewlineSeparator";
     private const string defaultSendNewlineSeparatorAppSettingsKey = "DefaultSendNewlineSeparator";
 
-    [ObservableProperty]
+    #region Terminal collection
-    private string title = "ShellView Test";
-
     [ObservableProperty]
     private ObservableCollection<ITerminalViewModel> terminalViewModels = new();
 
     [ObservableProperty]
     private ITerminalViewModel? selectedTerminalViewModel;
+    #endregion
 
     #region Settings Menu Bar
-    // TODO Initialize from File
     [ObservableProperty]
     private NewlineSeparatorType defaultReceiveNewlineSeparator = NewlineSeparatorType.None;
 
-    // TODO Initialize from File
     [ObservableProperty]
     private NewlineSeparatorType defaultSendNewlineSeparator = NewlineSeparatorType.None;
     #endregion
@@ -36,7 +33,6 @@ public partial class ShellViewModel : ObservableObject
     #region New Terminal Context Menu
     [ObservableProperty]
     private TerminalViewType selectedTerminalViewType = TerminalViewType.SendReceive;
-
     #endregion
 
     private readonly ITerminalViewModelFactory terminalViewModelFactory;
@@ -49,11 +45,8 @@ public partial class ShellViewModel : ObservableObject
         this.logger = logger;
         this.appSettings = appSettings;
 
-        // initialize newline separators from persistent settings
+        // intialize values from app settings
-        this.appSettings.TryReadSettingOrAddDefault(defaultReceiveNewlineSeparatorAppSettingsKey, out string settingValueReceiveNLSep, NewlineSeparatorType.None.ToString());
+        this.LoadFromAppSettings();
-        this.DefaultReceiveNewlineSeparator = EnumHelpers.ParseEnum<NewlineSeparatorType>(settingValueReceiveNLSep);
-        this.appSettings.TryReadSettingOrAddDefault(defaultSendNewlineSeparatorAppSettingsKey, out string settingValueSendNLSep, NewlineSeparatorType.None.ToString());
-        this.DefaultSendNewlineSeparator = EnumHelpers.ParseEnum<NewlineSeparatorType>(settingValueSendNLSep);
 
         // TEMP Init
         this.AppendTerminalWithSelectedViewType(ProtocolType.Serial);
@@ -94,20 +87,26 @@ public partial class ShellViewModel : ObservableObject
         this.TerminalViewModels.Remove(terminalToRemove);
     }
 
-    partial void OnDefaultReceiveNewlineSeparatorChanged(NewlineSeparatorType value)
+    #region App Settings handling
+    private void LoadFromAppSettings()
     {
-        Console.WriteLine($"Changed to {value}");
+        // initialize newline separators from persistent settings
+        this.appSettings.TryReadSettingOrAddDefault(defaultReceiveNewlineSeparatorAppSettingsKey, out string settingValueReceiveNLSep, NewlineSeparatorType.None.ToString());
+        this.DefaultReceiveNewlineSeparator = EnumHelpers.ParseEnum<NewlineSeparatorType>(settingValueReceiveNLSep);
+        this.appSettings.TryReadSettingOrAddDefault(defaultSendNewlineSeparatorAppSettingsKey, out string settingValueSendNLSep, NewlineSeparatorType.None.ToString());
+        this.DefaultSendNewlineSeparator = EnumHelpers.ParseEnum<NewlineSeparatorType>(settingValueSendNLSep);
     }
 
-    partial void OnDefaultSendNewlineSeparatorChanged(NewlineSeparatorType value)
+    partial void OnDefaultReceiveNewlineSeparatorChanged(NewlineSeparatorType value)
     {
-        Console.WriteLine($"Changed Send to {value}");
+        // update setting in app settings
+        this.appSettings.WriteSetting(defaultReceiveNewlineSeparatorAppSettingsKey, value.ToString());
     }
 
-    [RelayCommand]
+    partial void OnDefaultSendNewlineSeparatorChanged(NewlineSeparatorType value)
-    private void TestButtonClicked()
     {
-        this.DefaultReceiveNewlineSeparator = NewlineSeparatorType.CR_LF;
+        // update setting in app settings
+        this.appSettings.WriteSetting(defaultSendNewlineSeparatorAppSettingsKey, value.ToString());
     }
-
+    #endregion
 }

MultiTerm.Wpf/App.xaml.cs

@@ -49,9 +49,10 @@ public partial class App : Application
         Application.Current.DispatcherUnhandledException += this.Application_DispatcherUnhandledException;
         TaskScheduler.UnobservedTaskException += this.TaskScheduler_UnobservedTaskException;
 
-        // register log events from AppSettingsProvider
+        // register log events from AppSettingsProvider and load saved settings
         var appSettingsProvider = AppHost.Services.GetRequiredService<IAppSettingsProvider>();
         appSettingsProvider.LogWorthyEvent += AppSettingsProvider_LogWorthyEvent;
+        appSettingsProvider.Load();
 
         // instanciate startup form and show
         var startupForm = AppHost.Services.GetRequiredService<MainWindow>();
@@ -67,6 +68,10 @@ public partial class App : Application
 
     protected override async void OnExit(ExitEventArgs e)
     {
+        // save settings to persistent location
+        var appSettingsProvider = AppHost!.Services.GetRequiredService<IAppSettingsProvider>();
+        appSettingsProvider.Save();
+
         // log application exit and stop logger (if still available)
         logger?.LogInfo("Application exited.", nameof(App));
         logger?.StopLogging();