Can you use reflection to find the name of the currently executing method?

Can you use reflection to find the name of the currently executing method?

 

回答1

For non-async methods one can use

System.Reflection.MethodBase.GetCurrentMethod().Name;

https://docs.microsoft.com/en-us/dotnet/api/system.reflection.methodbase.getcurrentmethod

Please remember that for async methods it will return "MoveNext".

 

回答2

As of .NET 4.5, you can also use [CallerMemberName].

Example: a property setter (to answer part 2):

protected void SetProperty<T>(T value, [CallerMemberName] string property = null)
{
    this.propertyValues[property] = value;
    OnPropertyChanged(property);
}

public string SomeProperty
{
    set { SetProperty(value); }
}

The compiler will supply matching string literals at call sites, so there is basically no performance overhead.

 

回答3

 

 

The snippet provided by Lex was a little long, so I'm pointing out the important part since no one else used the exact same technique:

string MethodName = new StackFrame(0).GetMethod().Name;

This should return identical results to the MethodBase.GetCurrentMethod().Name technique, but it's still worth pointing out because I could implement this once in its own method using index 1 for the previous method and call it from a number of different properties. Also, it only returns one frame rather then the entire stack trace:

private string GetPropertyName()
{  //.SubString(4) strips the property prefix (get|set) from the name
    return new StackFrame(1).GetMethod().Name.Substring(4);
}

It's a one-liner, too ;)

 

How performant is StackFrame?

回答1

 

edit: Some background

---

We have a similar feature which is disabled 99% of the time; we were using an approach like:

public void DoSomething()
{
    TraceCall(MethodBase.GetCurrentMethod().Name);
    // Do Something
}

public void TraceCall(string methodName)
{
    if (!loggingEnabled) { return; }
    // Log...
}

TraceCall(MethodBase.GetCurrentMethod().Name)

It was simple, but regardless of whether or not tracing was enabled we were incurring the performance hit of using Reflection to lookup the method name.

Our options were to either require more code in every method (and risk simple mistakes or refusal) or to switch to using StackFrame to determine the calling method only when logging was enabled.

Option A:

public void DoSomething()
{
    if (loggingEnabled)
    {
        TraceCall(MethodBase.GetCurrentMethod().Name);
    }
    // Do Something
}

public void TraceCall(string methodName)
{
    if (!loggingEnabled) { return; }
    // Log...
}

Option B:

public void DoSomething()
{
    TraceCall();
    // Do Something
}

public void TraceCall()
{
    if (!loggingEnabled) { return; }
    StackFrame stackFrame = new StackFrame(1);
    // Log...
}

We opted for Option B. It offers significant performance improvements over Option A when logging is disabled, 99% of the time and is very simple to implement.

Here's an alteration of Michael's code, to display the cost / benefit of this approach

using System;
using System.Diagnostics;
using System.Reflection;

namespace ConsoleApplication
{
    class Program
    {
        static bool traceCalls;

        static void Main(string[] args)
        {
            Stopwatch sw;

            // warm up
            for (int i = 0; i < 100000; i++)
            {
                TraceCall();
            }

            // call 100K times, tracing *disabled*, passing method name
            sw = Stopwatch.StartNew();
            traceCalls = false;
            for (int i = 0; i < 100000; i++)
            {
                TraceCall(MethodBase.GetCurrentMethod());
            }
            sw.Stop();
            Console.WriteLine("Tracing Disabled, passing Method Name: {0}ms"
                             , sw.ElapsedMilliseconds);

            // call 100K times, tracing *enabled*, passing method name
            sw = Stopwatch.StartNew();
            traceCalls = true;
            for (int i = 0; i < 100000; i++)
            {
                TraceCall(MethodBase.GetCurrentMethod());
            }
            sw.Stop();
            Console.WriteLine("Tracing Enabled, passing Method Name: {0}ms"
                             , sw.ElapsedMilliseconds);

            // call 100K times, tracing *disabled*, determining method name
            sw = Stopwatch.StartNew();
            traceCalls = false;
            for (int i = 0; i < 100000; i++)
            {
                TraceCall();
            }
            Console.WriteLine("Tracing Disabled, looking up Method Name: {0}ms"
                       , sw.ElapsedMilliseconds);

            // call 100K times, tracing *enabled*, determining method name
            sw = Stopwatch.StartNew();
            traceCalls = true;
            for (int i = 0; i < 100000; i++)
            {
                TraceCall();
            }
            Console.WriteLine("Tracing Enabled, looking up Method Name: {0}ms"
                       , sw.ElapsedMilliseconds);

            Console.ReadKey();
        }

        private static void TraceCall()
        {
            if (traceCalls)
            {
                StackFrame stackFrame = new StackFrame(1);
                TraceCall(stackFrame.GetMethod().Name);
            }
        }

        private static void TraceCall(MethodBase method)
        {
            if (traceCalls)
            {
                TraceCall(method.Name);
            }
        }

        private static void TraceCall(string methodName)
        {
            // Write to log
        }
    }
}

The Results:

Tracing Disabled, passing Method Name: 294ms
Tracing Enabled,  passing Method Name: 298ms
Tracing Disabled, looking up Method Name: 0ms
Tracing Enabled,  looking up Method Name: 1230ms

 

回答2

I am considering using something like StackFrame stackFrame = new StackFrame(1) to log the executing method

Out of interest: Why? If you only want the current method, then

string methodName = System.Reflection.MethodBase.GetCurrentMethod().Name;

seems better. Maybe not more performant (I didn't compare, but Reflection shows that GetCurrentMethod() does not simply create a StackFrame but does some "magic"), but clearer in it's intent.