[API Proposal]: Add ability to get Caller MethodInfo from any code at runtime

[feeleen]

Background and motivation

Current speс assumes to use CallerMemberName attribute to know caller name.
But this require to write a lot of excessive/garbage code, and do not cover all situations. And this sometimes results in ".ctor" values which is useless.

If we want to know caller name, we don't want see constructors (".ctor") as a result (because it's a useless info), we want to know caller Method name (omitting implicit or explicit constructor calls chain!)

In scenario below the caller member is empty because of implicit constructor calls.

using System;
using System.Runtime.CompilerServices;

class Program
{
    static void Main()
    {
        B b = new();
    }
}

public class B : A {}

public class A
{
    public A([CallerMemberName] string? value = null)
    {
        Console.WriteLine(value);
    }
}

If I have dll with public class A which relies on CallerMemberName attribute in it's constructor - it won't work because I can't control how descendant classes are defined.

I tried this workaround to discover caller member:

public A([CallerMemberName] string? value = null)
{
      new StackTrace().GetFrames().ToList()
                .ForEach(x => Console.WriteLine(x.GetMethod()?.Name))
}

resut is:

.ctor
.ctor
Main

I don't need ".ctor". I look for Main. Ok.

But this works only for sync code. When it comes to async calls - the StackTrace I get doesn't contain a sync caller member ("Main") at all, because the call chain is broken here:

using System;
using System.Diagnostics;
using System.Runtime.CompilerServices;
using System.Linq;
using System.Threading.Tasks;

class Program
{
    static void Main()
    {
        Foo().GetAwaiter().GetResult();
    }

    static async Task Foo()
    {
        await Task.Delay(100);
        B b = new();
    }
}

public class B : A {}

public class A
{
    public A([CallerMemberName] string? value = null)
    {
        // in this stackTrace we know nothing about Main
        new StackTrace().GetFrames().ToList()
            .ForEach(x => Console.WriteLine(x.GetMethod()?.Name));

        // here we will see Main:
        throw new Exception();
    }
}

console output is:

.ctor
.ctor
MoveNext
ExecutionContextCallback
RunInternal
MoveNext
MoveNext
<OutputWaitEtwEvents>b__12_0
Invoke
RunOrScheduleAction
RunContinuations
FinishContinuations
TrySetResult
CompleteTimedOut
<.ctor>b__1_0
CallCallback
Fire
FireNextTimers
AppDomainTimerCallback

There is no "Main" here. Chain is broken.

but if we look at thrown Exception output - we can see "Program.Main()". chain isn't broken.

   at A..ctor(String value) in H:\My programming\_VS2022\ConsoleApp1\ConsoleApp1\Program.cs:line 35
   at B..ctor()
   at Program.<Foo>d__1.MoveNext() in H:\My programming\_VS2022\ConsoleApp1\ConsoleApp1\Program.cs:line 18
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.GetResult()
   at Program.Main() in C:\Temp\ConsoleApp1\ConsoleApp1\Program.cs:line 12

So,

It would be great if caller name or caller MethodInfo (omit constructors! they are useless) to be stored somewhere in ExecutionContext when it's captured, and to be able to get this info somehow from sync or async code. To get it I want to call CurrentThread.CallerMemberName or something like CurrentThread.GetCallerMethod(). It'll look for callers in current thread (if async code), -> if not found -> Look for it in ExecutionContext

the second Issue here is that new StackTrace() doesn't contain a frames with sync code, from which async code is called.

API Proposal

MethodInfo mi = CurrentThread.GetCallerMethod();
//or
MethodInfo mi = MethodBase.GetCallerMethod();

API Usage

MethodInfo mi = CurrentThread.GetCallerMethod();
//or
MethodInfo mi = MethodBase.GetCallerMethod();

Alternative Designs

No response

Risks

No response

[dotnet-issue-labeler]

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

[ghost]

Tagging subscribers to this area: @buyaa-n
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Background and motivation

Current speс assumes to use CallerMemberName attribute to know caller name.
But this require to write a lot of excessive/garbage code, and do not cover all situations. And this sometimes results in ".ctor" values which is useless.

If we want to know caller name, we don't want see constructors (".ctor") as a result (because it's a useless info), we want to know caller Method name (omitting implicit or explicit constructor calls chain!)

In scenario below the caller member is empty because of implicit constructor calls.

using System;
using System.Runtime.CompilerServices;

class Program
{
    static void Main()
    {
        B b = new();
    }
}

public class B : A {}

public class A
{
    public A([CallerMemberName] string? value = null)
    {
        Console.WriteLine(value);
    }
}

If I have dll with public class A which relies on CallerMemberName attribute in it's constructor - it won't work because I can't control how descendant classes are defined.

I tried this workaround to discover caller member:

public A([CallerMemberName] string? value = null)
{
      new StackTrace().GetFrames().ToList()
                .ForEach(x => Console.WriteLine(x.GetMethod()?.Name))
}

resut is:

.ctor
.ctor
Main

I don't need ".ctor". I look for Main. Ok.

But this works only for sync code. When it comes to async calls - the StackTrace I get doesn't contain a sync caller member ("Main") at all, because the call chain is broken here:

using System;
using System.Diagnostics;
using System.Runtime.CompilerServices;
using System.Linq;
using System.Threading.Tasks;

class Program
{
    static void Main()
    {
        Foo().GetAwaiter().GetResult();
    }

    static async Task Foo()
    {
        await Task.Delay(100);
        B b = new();
    }
}

public class B : A {}

public class A
{
    public A([CallerMemberName] string? value = null)
    {
        // in this stackTrace we know nothing about Main
        new StackTrace().GetFrames().ToList()
            .ForEach(x => Console.WriteLine(x.GetMethod()?.Name));

        // here we will see Main:
        throw new Exception();
    }
}

console output is:

.ctor
.ctor
MoveNext
ExecutionContextCallback
RunInternal
MoveNext
MoveNext
<OutputWaitEtwEvents>b__12_0
Invoke
RunOrScheduleAction
RunContinuations
FinishContinuations
TrySetResult
CompleteTimedOut
<.ctor>b__1_0
CallCallback
Fire
FireNextTimers
AppDomainTimerCallback

There is no "Main" here. Chain is broken.

but if we look at thrown Exception output - we can see "Program.Main()". chain isn't broken.

   at A..ctor(String value) in H:\My programming\_VS2022\ConsoleApp1\ConsoleApp1\Program.cs:line 35
   at B..ctor()
   at Program.<Foo>d__1.MoveNext() in H:\My programming\_VS2022\ConsoleApp1\ConsoleApp1\Program.cs:line 18
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.GetResult()
   at Program.Main() in C:\Temp\ConsoleApp1\ConsoleApp1\Program.cs:line 12

So,

It would be great if caller name or caller MethodInfo (omit constructors! they are useless) to be stored somewhere in ExecutionContext when it's captured, and to be able to get this info somehow from sync or async code. To get it I want to call CurrentThread.CallerMemberName or something like CurrentThread.GetCallerMethod(). It'll look for callers in current thread (if async code), -> if not found -> Look for it in ExecutionContext

the second Issue here is that new StackTrace() doesn't contain a frames with sync code, from which async code is called.

API Proposal

MethodInfo mi = CurrentThread.GetCallerMethod();

API Usage

MethodInfo mi = CurrentThread.GetCallerMethod();

Alternative Designs

No response

Risks

No response

Author:	feeleen
Assignees:	-
Labels:	api-suggestion, area-System.Reflection, untriaged
Milestone:	-

[DaZombieKiller]

This seems like a subset of dotnet/csharplang#4984

[buyaa-n]

I am not sure it is doable in reflection, probably better to be moved to System.Diagnostics? cc @steveharter

[ghost]

Tagging subscribers to this area: @tommcdon
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Background and motivation

Current speс assumes to use CallerMemberName attribute to know caller name.
But this require to write a lot of excessive/garbage code, and do not cover all situations. And this sometimes results in ".ctor" values which is useless.

If we want to know caller name, we don't want see constructors (".ctor") as a result (because it's a useless info), we want to know caller Method name (omitting implicit or explicit constructor calls chain!)

In scenario below the caller member is empty because of implicit constructor calls.

using System;
using System.Runtime.CompilerServices;

class Program
{
    static void Main()
    {
        B b = new();
    }
}

public class B : A {}

public class A
{
    public A([CallerMemberName] string? value = null)
    {
        Console.WriteLine(value);
    }
}

If I have dll with public class A which relies on CallerMemberName attribute in it's constructor - it won't work because I can't control how descendant classes are defined.

I tried this workaround to discover caller member:

public A([CallerMemberName] string? value = null)
{
      new StackTrace().GetFrames().ToList()
                .ForEach(x => Console.WriteLine(x.GetMethod()?.Name))
}

resut is:

.ctor
.ctor
Main

I don't need ".ctor". I look for Main. Ok.

But this works only for sync code. When it comes to async calls - the StackTrace I get doesn't contain a sync caller member ("Main") at all, because the call chain is broken here:

using System;
using System.Diagnostics;
using System.Runtime.CompilerServices;
using System.Linq;
using System.Threading.Tasks;

class Program
{
    static void Main()
    {
        Foo().GetAwaiter().GetResult();
    }

    static async Task Foo()
    {
        await Task.Delay(100);
        B b = new();
    }
}

public class B : A {}

public class A
{
    public A([CallerMemberName] string? value = null)
    {
        // in this stackTrace we know nothing about Main
        new StackTrace().GetFrames().ToList()
            .ForEach(x => Console.WriteLine(x.GetMethod()?.Name));

        // here we will see Main:
        throw new Exception();
    }
}

console output is:

.ctor
.ctor
MoveNext
ExecutionContextCallback
RunInternal
MoveNext
MoveNext
<OutputWaitEtwEvents>b__12_0
Invoke
RunOrScheduleAction
RunContinuations
FinishContinuations
TrySetResult
CompleteTimedOut
<.ctor>b__1_0
CallCallback
Fire
FireNextTimers
AppDomainTimerCallback

There is no "Main" here. Chain is broken.

but if we look at thrown Exception output - we can see "Program.Main()". chain isn't broken.

   at A..ctor(String value) in H:\My programming\_VS2022\ConsoleApp1\ConsoleApp1\Program.cs:line 35
   at B..ctor()
   at Program.<Foo>d__1.MoveNext() in H:\My programming\_VS2022\ConsoleApp1\ConsoleApp1\Program.cs:line 18
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.GetResult()
   at Program.Main() in C:\Temp\ConsoleApp1\ConsoleApp1\Program.cs:line 12

So,

It would be great if caller name or caller MethodInfo (omit constructors! they are useless) to be stored somewhere in ExecutionContext when it's captured, and to be able to get this info somehow from sync or async code. To get it I want to call CurrentThread.CallerMemberName or something like CurrentThread.GetCallerMethod(). It'll look for callers in current thread (if async code), -> if not found -> Look for it in ExecutionContext

the second Issue here is that new StackTrace() doesn't contain a frames with sync code, from which async code is called.

API Proposal

MethodInfo mi = CurrentThread.GetCallerMethod();
//or
MethodInfo mi = MethodBase.GetCallerMethod();

API Usage

MethodInfo mi = CurrentThread.GetCallerMethod();
//or
MethodInfo mi = MethodBase.GetCallerMethod();

Alternative Designs

No response

Risks

No response

Author:	feeleen
Assignees:	-
Labels:	api-suggestion, area-System.Diagnostics, area-System.Reflection
Milestone:	Future

[joperezr]

Just to add here, I agree with @buyaa-n that this API wouldn't belong on System.Reflection MethodInfo as MethodInfo is just an object that represents the pointer to a method and has info that are not related to current execution. Perhaps this kind of API would be better placed in a type like StackTrace?