Display Mode Provider DSL For Fun

DisplayModeExpression.cs

public class DisplayModeExpression
    {
        readonly Func<HttpContextBase, bool> _condition;
        
        public DisplayModeExpression(Func<HttpContextBase, bool> condition)
        {
            _condition = condition;
        }

        public void UseDisplayMode(string displayModeSuffix)
        {
            if(string.IsNullOrEmpty(displayModeSuffix) || string.IsNullOrWhiteSpace(displayModeSuffix))
                throw new ArgumentException("The Display Mode Suffix cannot be null, empty or whitespace");

            DisplayModeProvider.Instance.Modes.Add(new DefaultDisplayMode(displayModeSuffix) {ContextCondition = _condition});
        }
    }

Global.asax.cs

//Other Global stuff

    protected void Application_Start()
        {
           //Removed other stuff for brevity

            When(ctx => ctx.GetOverriddenUserAgent().Contains("Windows Phone OS"))
                .UseDisplayMode("WP7");            
        }

    private static DisplayModeExpression When(Func<HttpContextBase, bool> condition)
        {
            return new DisplayModeExpression(condition);
        }

//Closing braces and the like