Generic logging of function parameters in exception handling

Question

A lot of my C# code follows this pattern:

void foo(string param1, string param2, string param3) {     try     {          // do something...     }     catch(Exception ex)     {         LogError(String.Format("Error in foo(param1={0}, param2={1}, param3={2}), exception={3}", param1, param2, param3, ex.Message));     } } 

Is there a way in .NET to get a Key/Value list of the parameters to a function so that I can call another function to construct my error logging string? OR Do you have a more generic / better way of doing this?

Answer 1

You could use Reflection and the convention that you must pass the parameters to the LogError with the right order:

private static void MyMethod(string s, int x, int y) {     try     {         throw new NotImplementedException();     }     catch (Exception ex)     {         LogError(MethodBase.GetCurrentMethod(), ex, s, x, y);     } }  private static void LogError(MethodBase method, Exception ex, params object[] values) {     ParameterInfo[] parms = method.GetParameters();     object[] namevalues = new object[2 * parms.Length];      string msg = "Error in " + method.Name + "(";     for (int i = 0, j = 0; i < parms.Length; i++, j += 2)     {         msg += "{" + j + "}={" + (j + 1) + "}, ";         namevalues[j] = parms[i].Name;         if (i < values.Length) namevalues[j + 1] = values[i];     }     msg += "exception=" + ex.Message + ")";     Console.WriteLine(string.Format(msg, namevalues)); } 

Answer 2

You could use aspect oriented programming with PostSharp (have a look at http://www.postsharp.org, and the tutorial at http://www.codeproject.com/KB/cs/ps-custom-attributes-1.aspx). Basically you could do something like this:

public class LogExceptionAttribute : OnExceptionAspect {  public override void OnException(MethodExecutionEventArgs eventArgs)  {   log.error("Exception occurred in method {0}", eventArgs);   } }  [LoggingOnExceptionAspect] public foo(int number, string word, Person customer) {    // ... something here throws an exception } 

Perhaps not quite what you want, but I'm sure it can be adapted to suit your needs.