How to get variable name using reflection?

Question

For example,

static void Main()
{
    var someVar = 3;

    Console.Write(GetVariableName(someVar));
}

The output of this program should be:

someVar

How can I achieve that using reflection?

Answer 1

You can't using reflection. GetVariableName is passed the number 3, not a variable. You could do this via code inspect of the IL, but that's probably in the too-hard basket.

Answer 2

It is not possible to do this with reflection, because variables won't have a name once compiled to IL. However, you can use expression trees and promote the variable to a closure:

static string GetVariableName<T>(Expression<Func<T>> expression)
{
    var body = expression.Body as MemberExpression;

    return body.Member.Name;
}

static void Main()
{
    var someVar = 3;

    Console.Write(GetVariableName(() => someVar));
}

Note that this is pretty slow, so don't use it in performance critical paths of your application.