/// <summary>
/// Creates an instance of <see cref="IPreferenceStoreManager"/>. First, it is looked up if a custom implementation
/// is provided by an extension point. If not, a default implementation is returned. Otherwise the contribution with
/// the highest priority is taken. There is always just one implementation of <see cref="IPreferenceStoreManager"/>.
/// </summary>
/// <returns>
/// An instance of <see cref="IPreferenceStoreManager"/> either provided by an extension point or the
/// default implementation.
/// </returns>
private static IPreferenceStoreManager CreatePreferenceStoreManager()
{
ILog logWriter = LogManager.GetLog(typeof(PreferenceStoreManager));
IConfigurationElement[] configurationElements = ExtensionService.Instance.GetConfigurationElements(PreferenceStoreManagerExtensionPointId);
// Default
if (configurationElements == null || configurationElements.Length == 0)
{
logWriter.Info("No preference store manager contributed. Using default implementation.");
return(GetDefaultPreferenceStoreManager());
}
// Max priority
IConfigurationElement maxPriorityElement = configurationElements.OrderByDescending(element => {
string priorityValue = element["priority"];
if (!int.TryParse(priorityValue, out int priority))
{
return(0);
}
return(priority);
}).First();
// Grab the bundle
IBundle providingBundle = ExtensionService.Instance.GetProvidingBundle(maxPriorityElement);
logWriter.Debug($"Plug-in '{providingBundle}' provides a custom preference store manager implementation with highest priority.");
// Grab the type
string className = maxPriorityElement["class"];
if (string.IsNullOrEmpty(className))
{
logWriter.Error($"Plug-in '{providingBundle}' provides a custom preference store manager implementation with an empty " +
"class attribute. Using default implementation.");
return(GetDefaultPreferenceStoreManager());
}
// Allocate
try {
Type instanceType = TypeLoader.TypeForName(providingBundle, className);
IPreferenceStoreManager preferenceStoreManager = instanceType.NewInstance <IPreferenceStoreManager>();
logWriter.Info($"Preference store manager of type '{preferenceStoreManager.GetType()}' successfully installed");
return(preferenceStoreManager);
} catch (Exception ex) {
logWriter.Error($"Error on installing preference store manager from plug-in '{providingBundle}' (Class '{className}').", ex);
return(GetDefaultPreferenceStoreManager());
}
}
/// <summary>
/// Returns the currently used <see cref="IPreferenceStoreManager"/>.
/// </summary>
/// <returns>Currently used <see cref="IPreferenceStoreManager"/></returns>
public static IPreferenceStoreManager GetInstance()
{
return(_preferenceStoreManager ?? (_preferenceStoreManager = CreatePreferenceStoreManager()));
}