Fun with lambdas and scoping in C#

AbstractSkeletonTrackingDevice.cs

public abstract class AbstractSkeletonTrackingDevice : AbstractControlDevice
{
    // ...
    
    protected void registerExerciseInput(SkeletonExercise new_exercise)
    {
      // ...
      
      foreach(string axis_name in new_exercise.axisNames)
      {
        // The following doesn't work :
        registerAxis(axis_name, () => (new_exercise.skeleton == null) ? 0.0f : new_exercise.getAxis(axis_name));
        // This is because the lambda uses a reference to 'axis_name' rather than a copy of its value.
        // As a result in all the lambdas' scopes the value of 'axis_name' is the final value it took at the end of
        // the iteration. In this case the axis names are "X" and "Y" so 'axis_name' is always equal to "Y" in the
        // lambdas' scope.
        
        // The following doesn't work either :
        registerAxis(axis_name, () =>
        {
          string axis_name_copy = String.Copy(axis_name);
          registerAxis(axis_name_copy, () => (new_exercise.skeleton == null) ? 0.0f : new_exercise.getAxis(axis_name_copy));
        }
        // This is because as a copy is being made of the reference to 'axis_name', the iterator variable. The copy needs
        // to be made *before* being captured by the closure!
        
        // Thus the only working solution is the following
        string axis_name_copy = String.Copy(axis_name);
        registerAxis(axis_name, () => (new_exercise.skeleton == null) ? 0.0f : new_exercise.getAxis(axis_name_copy));
        // note that 'axis_name_copy' only needs to be used within the lambdas' scope : 'axis_name' can be used
        // for the key registration.
      }
      
      // ...
    }
    
  // ...
}