Get parameter name - postsharp

Question

How do you get the parameter NAMES of a method. The examples show you how to get the values of the parameters, but not the NAMES. I want to see parma = 99, parmb = 1. Not just 99, 1.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Diagnostics;
using PostSharp.Aspects;
namespace GettingParmNames
{
public class Program
{
static void Main(string[] args)
{
Foo myfoo = new Foo();
int sum = myfoo.DoA(99, 1);
Console.WriteLine(sum.ToString());
Console.ReadKey();
}
}
public class Foo
{
[ExceptionAspect]
public int DoA(int parma, int parmb)
{
int retVal;
try
{
retVal = parma + parmb;
if (parma == 99)
{
throw new Exception("Fake Exception");
}
}
catch (Exception ex)
{
retVal = -1;
throw new Exception("There was a problem");
}
return retVal;
}
}
[Serializable]
public class ExceptionAspect : OnExceptionAspect
{
public override void OnException(MethodExecutionArgs args)
{
string parameterValues = "";
foreach (object arg in args.Arguments)
{
if (parameterValues.Length > 0)
{
parameterValues += ", ";
}
if (arg != null)
{
parameterValues += arg.ToString();
}
else
{
parameterValues += "null";
}
}
Console.WriteLine("Exception {0} in {1}.{2} invoked with arguments {3}", args.Exception.GetType().Name, args.Method.DeclaringType.FullName, args.Method.Name, parameterValues );
}
}
}

Answer 1

You can access the method parameters' info in your OnException method by calling args.Method.GetParameters(). But usually it's better to initialize the data during compile time for performance reasons - in the CompileTimeInitialize method override.
[Serializable]
public class ExceptionAspect : OnExceptionAspect
{
private string[] parameterNames;
public override void CompileTimeInitialize(MethodBase method, AspectInfo aspectInfo)
{
parameterNames = method.GetParameters().Select(p => p.Name).ToArray();
}
public override void OnException(MethodExecutionArgs args)
{
StringBuilder parameterValues = new StringBuilder();
for (int i = 0; i < args.Arguments.Count; i++)
{
if ( parameterValues.Length > 0 )
{
parameterValues.Append(", ");
}
parameterValues.AppendFormat(
"{0} = {1}", parameterNames[i], args.Arguments[i] ?? "null");
}
// ...
}

Answer 2

Great answer from AlexD.
The following is a similar approach, giving you the argument names and values.
using System;
using System.Linq;
using System.Reflection;
using PostSharp.Aspects;
[Serializable]
public class LogWhenInvoked : MethodInterceptionAspect
{
private string[] parameterNames;
public override void CompileTimeInitialize(MethodBase method, AspectInfo aspectInfo)
{
parameterNames = method.GetParameters().Select(p => p.Name).ToArray();
}
public override void OnInvoke(MethodInterceptionArgs invocationArgs)
{
Console.WriteLine($"Entering {invocationArgs.Method.DeclaringType.Name}.{invocationArgs.Method.Name}");
var args = parameterNames.Select((param, index) => new
{
Name = param,
Value = invocationArgs.Arguments[index]
})
.ToList();
invocationArgs.Proceed();
}
}