Refactor long switch statement

Question

I\'m program in c# which you controlling by dictating command so now i have a long switch statement. Something like

switch (command)

{
    case \"Show comma         


        

Answer 1

I realize this is an old post, but in these situations I find attributes and a factory very handy.

The following code uses a custom attribute (Command) to allow you to attribute your methods, providing a string value of how they should respond to you.

The factory method uses reflection to generate a dictionary of these methods and calls it whenever you call CommandFactory.

Things could get cleaned up a bit, calling invoke is a little ugly, but it just depends on how you want to execute the code.

using System.Collections.Generic;
using System.Linq;

namespace MyApp
{
    using System.Reflection;
    using MyApp.Commands;

    class Program
    {
        static void Main(string[] args)
        {
            var methods = new MyCommands();
            MethodInfo myMethod;
            myMethod = CommandFactory.GetCommandMethod("Show Commands");
            myMethod.Invoke(methods, null);
            myMethod = CommandFactory.GetCommandMethod("Close window");
            myMethod.Invoke(methods, null);
            myMethod = CommandFactory.GetCommandMethod("Switch window");
            myMethod.Invoke(methods, null);
        }
    }

    public static class CommandFactory
    {
        private static Dictionary speechMethods = new Dictionary();
        public static MethodInfo GetCommandMethod(string commandText)
        {
            MethodInfo methodInfo;
            var commands = new MyCommands();
            if (speechMethods.Count == 0)
            {
                var methodNames =
                    typeof(MyCommands).GetMethods(BindingFlags.Public | BindingFlags.DeclaredOnly | BindingFlags.Instance);
                var speechAttributeMethods = methodNames.Where(y => y.GetCustomAttributes().OfType().Any());
                foreach (var speechAttributeMethod in speechAttributeMethods)
                {
                    foreach (var attribute in speechAttributeMethod.GetCustomAttributes(true))
                    {
                        speechMethods.Add(((CommandAttribute)attribute).Command, speechAttributeMethod);
                    }
                }
                methodInfo = speechMethods[commandText];
            }
            else
            {
                methodInfo = speechMethods[commandText];
            }
            return methodInfo;
        }
    }
}

namespace MyApp.Commands
{
    class MyCommands
    {
        [Command("Show All")]
        [Command("Show All Commands")]
        [Command("Show commands")]
        public void ShowAll()
        {
            ProgramCommands.ShowAllCommands();
        }

        [Command("Close Window")]
        public void CloseWindow()
        {
            ControlCommands.CloseWindow();
        }

        [Command("Switch Window")]
        public void SwitchWindow()
        {
            ControlCommands.SwitchWindow();
        }
    }

    [System.AttributeUsage(System.AttributeTargets.Method, AllowMultiple = true)]
    public class CommandAttribute : System.Attribute
    {
        public string Command
        {
            get;
            set;
        }

        public CommandAttribute(string textValue)
        {
            this.Command = textValue;
        }
    }
}