Generic Type Conversion

While working on the Virtual Earth map application, I discovered the need to parse data from a string of characters. So I searched the net and found this answer on stack overflow: generic-type-conversion-from-string . I like this code example because it looks like the simplest and most general approach:

public class TypedProperty<T> : Property
{
     public T TypedValue
     {
        get { return (T)Convert.ChangeType(base.Value, typeof(T)); }
        set { base.Value = value.ToString();}
     }
}

But if you cut and paste the code into a Silverlight 2 or Silverlight 3 application it does not run. This is because the two argument version of the ChangeType method is not part of the Silverlight runtime. I guess I could have used the three argument version, but instead I implemented a function the uses reflection:

public bool TryParse<T>(string sValue, out T oValue) where T : IConvertible
{
     oValue = default(T);

     try
     {
          string[] parts = sValue.Split(':');
          MethodInfo oMethod = typeof(T).GetMethod("Parse", new Type[] { typeof(string) } );
          oValue = (T)oMethod.Invoke(null, new object[] { parts[1].Trim() });
          return true;
     }
     catch { }
     return false;
}

Silverlight Size vs. Functionality

You find this all the time in Silverlight development -- some of the tools, functions and features you have come to rely on in .NET are just not part of the lightweight Silverlight runtime. I read on one blog that programming with Silverlight is like going camping with .NET. In fact, I first learned this the hard way trying to recompile some previous .NET code. I couldn't include the existing library -- it had to be rebuilt using the Silverlight libraries. When I attempted to recompile it, I found that it needed to be reengineered to use functionality available in the Silverlight runtime.

I have always been able to find a creative solution to simple programming issues like the one above, and I think the ability to deliver my solution over the web to any machine, without creating a custom install, makes it worth the effort to find these alternative approaches.