Push and pull value on callstack .net

Question

I've done this before, so I know it can be done..(although badly documented) but forgot how. I've been searching for 2 hours now and can't find anything like it.

I want to push and pull values on the callstack, like so:

public void Method1()
{
    InsertMagicClassHere.Push("Key", 1);//or something
    Method2();
}

public void Method2()
{
   int value =  InsertMagicClassHere.Pull("Key");//or something
}

I need this parameter in nearly all my methods for logging.. and don't want to pass this 3 layers deep with arguments.

Answer 1

You are looking for Reflection.Emit; however, this is not how it works.

You can't really emit inline opcodes.

Instead, you can emit whole methods/classes and load them as 'temporary' assemblies. You then call into the emitted method.

Obligatory sample:

public void CreateMethod()
{
    AppDomain currentDomain = AppDomain.CurrentDomain;
    AssemblyBuilder asmbuilder = this.GetAssemblyBuilder("MyAssembly");
    ModuleBuilder mbuilder = this.GetModule(asmbuilder);
    TypeBuilder tbuilder = this.GetTypeBuilder(mbuilder, "MyClass");

    Type[] tparams = { typeof(System.Int32), typeof(System.Int32) };
    MethodBuilder methodSum = this.GetMethod(tbuilder, "Sum", typeof(System.Single), 
                                                                 tparams);

    ILGenerator generator = methodSum.GetILGenerator();

    generator.DeclareLocal(typeof(System.Single));  
    generator.Emit(OpCodes.Ldarg_1);    
    generator.Emit(OpCodes.Ldarg_2);    
    generator.Emit(OpCodes.Add_Ovf);    
    generator.Emit(OpCodes.Conv_R4);    
    generator.Emit(OpCodes.Stloc_0);    

    generator.Emit(OpCodes.Ldloc_0);    
    generator.Emit(OpCodes.Ret);        
}

So what you could do

1. take an existing method
2. disassemble it
3. write the code to emit a new method on the IL level (using Reflection.Emit)
4. load the emitted assembly
5. call into your code.

See these articles for good starters:

• http://www.codeproject.com/KB/cs/DLR.aspx
• MSDN: using Reflection Emit

Answer 2

Okay. the answer is:

CallContext

This works:

       public void Method1()
    {
        CallContext.SetData("Key", 1);
        Method2();
    }

    public void Method2()
    {
        int value = (int)CallContext.GetData("Key");
    }

Like I said this is not a well known feature.. If you knew it, you would have known what I was referring to.

I think it's a cool feature, not many uses for it, but still..