What is the best practice to handle application's settings between several forms

Question

What is the best practice to handle application's settings contains in the external INI file between several forms?

Suppose that I have two forms -- MainForm and SettingsForm. User can open the SettingsForm from the MainForm. Now I have smth like this:

• On Load event of the SettingsForm I read application's settings from the file and change the UI appropriately
• On "Save" button press I write new options' values to the file
• On the "SettingsFormClosed" event of the MainForm I read the settings from the file again

I think that the last thing is the most terrible in this case. Maybe I should use smth like SettingsSingleton or smth like this? What is the best practice to do it in C# and Windows Forms?

Thanks in advance.

Answer 1

You should use Observer pattern. You will need a class which represents settings file, this file is Observable. Your SettingsForm and MainForm are Observers. And SettingsForm can modify the Observable.

Answer 2

I like to do it like this, make a Setting class for storing the values, then create a service class that is responsible for saving and supplying the settings to other objects. Service is implemented as a singleton and implements INotifyPropertyChanged. Then in your forms you just have to subscribe to ProperyChanging event from the service.

Example service code:

 public sealed class SettingsService : INotifyPropertyChanged
    {
        private static Lazy<SettingsService> instance = new Lazy<SettingsService>(() => new SettingsService());

        public static SettingsService Instance
        {
            get { return instance.Value; }
        }

        private Setting settings;
        public Setting Settings
        {
           get
           {
              var clone = settings.Clone();
              return clone;
           }
        }

        private SettingsService()
        {
           //load your settings
        }            

        public void SaveChanges(Setting settings)
        {
           //Do whatever you do to save the changes, and raise the event the   settings changed
           this.settings = settings;
           NotifyPropertyChanged();
        }


        private void NotifyPropertyChanged()
        {
            if (PropertyChanged != null)
               PropertyChanged(this, new PropertyChangedEventArgs("Settings"));
        }
        public event PropertyChangedEventHandler PropertyChanged;
}