Using Method.Invoke to avoid a lengthy Case Statement in C# (Using Reflection)

So, I asked the following question in at http://forums.asp.net/t/1408631.aspx

The problem is, I’ve got 30 methods that all have the same signature, but have different implementations. Mike Banavige (the lead moderator at the forums) suggested I look at the following article on reflection: http://www.csharphelp.com/archives/archive200.html. Turns out, that helped my solve my problem exactly. Rather than go through a lengthy line by line explanation, I’m going to post some of my before and after code. It’s pretty clear what is happening, but I thought it would be nice to show a real example.

Before Code:

 private static void AddTemplateCode(string templateNumber, int indent, ICollection<string> newLines,FullMeta fullMetal)

            int iTemplateNumber = Convert.ToInt32(templateNumber);

            var sb = new StringBuilder(indent);

            sb.Append(' ', indent);

            string indentString = sb.ToString();

             // be nice to get rid of this ugly case statement.  Using it because I want to have a way to separate

             // methods associated with groups of methods.  that is, put Template11-15 in a separate file later.

            switch (iTemplateNumber)

                case 11:

                        Template11(newLines, indentString,fullMetal);

                        break;

                case 12:

                        Template12(newLines, indentString,fullMetal);

                        break;

                case 13:

                        Template13(newLines, indentString, fullMetal);

                        break;

                case 14:

<This goes on and on and on and on>

Then, After, following the sample above:

 private static void AddTemplateCode(string templateNumber, int indent, ICollection<string> newLines,FullMeta fullMetal)

            int iTemplateNumber = Convert.ToInt32(templateNumber);

            var sb = new StringBuilder(indent);

            sb.Append(' ', indent);

            string indentString = sb.ToString();

            var processTemplate = new ProcessTemplateDynamic();

            processTemplate.DoIt(iTemplateNumber, newLines, indentString, fullMetal);

<Then the class with DoIt in it...>

using System;

using System.Collections.Generic;

using System.Reflection;

namespace ThreePLogicAccessCodeGen.Code

    public class ProcessTemplateDynamic

        internal void DoIt(int iTemplateNumber, ICollection<string> newLines, string indentString, FullMeta fullMetal)

            // Template11(newLines, indentString, fullMetal);

            string templateMethodName = String.Format("Template{0}", iTemplateNumber);

            var userParameters = new object[3];

            userParameters[0] = newLines;

            userParameters[1] = indentString;

            userParameters[2] = fullMetal;

try

                Type thisType = GetType();

                MethodInfo theMethod = thisType.GetMethod(templateMethodName);

                // that we have in this class that we don't want called.

                if (theMethod == null || (!CheckMethod(theMethod)))

                    throw new ApplicationException(string.Format("[e] Command <{0}> not supported.", templateMethodName));

                // Invoke the Method!

                theMethod.Invoke(this, userParameters);

            catch (ArgumentNullException e)

                // This exception is from the user entering in a null string on the command line

                throw new ApplicationException("[e] Please enter in a non-null string. (" + e.Message + ")");

            catch (TargetParameterCountException e)

                // This exception is thrown when the method is not passed the right number of parameters

                throw new ApplicationException(string.Format("[e] Command <{0}> requires parameters. ({1})",

                                                             templateMethodName, e.Message));

            catch (Exception e)

                // All other exceptions!

                throw new ApplicationException(string.Format("[e] General Exception:n{0}", e));

Well, looking at it, seems maybe the Case statement is better, but the nice thing now is that each time I add a new template, I don’t have to make another case statement. That combined with it’s easier to make typos when you have a case statement so I’m sticking with my new solution here.

Hope this Helps!