Friday, July 18, 2014

Sasa v0.13.0 Released

The latest Sasa release fixes a few bugs with MIME parsing, and adds a few new concurrency features. Here is the online documentation, or a downloadable CHM file from Sourceforge is available alongside the binaries. The binaries are also available via nuget, of course. Here's the changelog:

  • added Sasa.Concurrency.RWLock, a truly slim concurrent read/write lock
  • switched Sasa.Dynamics.PIC to use RWLock
  • switched Sasa.Dynamics.PIC to rely only on arrays for performance reasons
  • Mail message parsing now doesn't use ad-hoc means to extract a body from the attachments
  • added Sasa.Changeable<T> which encapsulates all INotifyPropertyChanged and INotifyPropertyChanging logic with no space overhead
  • fixed an MIME HTML parsing bug
  • fixed regex lexing
  • added more efficient Enums class exposing static properties for various enum properties
  • alternate views inside multipart/related no longer incorrectly dropped
  • added well-behaved standards conforming URI encode/decode to Sasa.Uris
  • added overload to customize string comparison type when tokenizing

Nothing too Earth-shattering. While I generally deplore reinventing the wheel, I found the URL encoding/decoding functions provided by System.Uri and in System.Web to be too inconsistent for my purposes in Clavis. The encode/decode functions in Sasa.Uris now work on StringBuilder, so they are more efficient, and they fully conform to the latest RFC.

The RWLock was covered here before, so no need to detail that. The PIC uses internal tables which are now protected by RWLock.

The only other really new feature is the Sasa.Changeable<T> type, which encapsulates the logic implementing INotifyPropertyChanging and INotifyPropertyChanged:

public struct Changeable<T>
{
  public T Value { get; private set; }

  public bool Update(string name, T value,
                    PropertyChangingEventHandler onChanging,
                    PropertyChangedEventHandler onChanged)
  {
    if (EqualityComparer<T>.Default.Equals(Value, value)) return false;
    onChanging.Raise(name, new PropertyChangingEventArgs(name));
    Value = value;
    onChanged.Raise(name, new PropertyChangedEventArgs(name));
    return true;
  }
}

So instead of repeating this logic in every property, you simply declare the field to be a Changeable<T> and call update with references to the appropriate event handlers:

public class Foo : INotifyPropertyChanging, INotifyPropertyChanged
{
  Changeable<int> foo;
  PropertyChangingEventHandler onChanging;
  PropertyChangedEventHandler onChanged;

  public PropertyChangingEventHandler PropertyChanging
  {
    add { Sasa.Events.Add(ref onChanging, value); }
    remove { Sasa.Events.Remove(ref onChanging, value); }
  }

  public PropertyChangedEventHandler PropertyChanged
  {
    add { Sasa.Events.Add(ref onChanged, value); }
    remove { Sasa.Events.Remove(ref onChanged, value); }
  }

  public int Foo
  {
    get { return foo.Value; }
    set { foo.Update("Foo", value, PropertyChanging, PropertyChanged); }
  }
}

If the value differs from the current value, then the events will be raised. The Update method returns true if the value was updated, and false otherwise so you can implement your own change logic as well.

Note that the handlers can be null if you're not implementing both INotifyPropertyChanging and INotifyPropertyChanged.

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