gistfile1.txt

public class SomeViewModel : INotifyPropertyChanged, INotifyDataErrorInfo
{
  errorsContainer = new ErrorsContainer<string>(x => ErrorsChanged?.Invoke(this, new DataErrorsChangedEventArgs(x)));
  
  public IEnumerable GetErrors(string propertyName)
  {
    return errorsContainer.GetErrors(propertyName);
  }

  private string propertyName;
  public string PropertyName
  {
    get
    {
      return propertyName;
    }
    set
    {
      propertyName = value;
      OnPropertyChanged();
    }
  }

  private void Validate()
  {
    if(!someValidationLogic)
    {
      errorsContainer.SetErrors(()=> PropertyName, new List<string>(){"Wrong Value"});
    }
    else
    {
      errorsContainer.ClearErrors(() => PropertyName);
    }
  }

  public bool HasErrors => errorsContainer.HasErrors;
  public event EventHandler<DataErrorsChangedEventArgs> ErrorsChanged;
 
 [NotifyPropertyChangedInvocator]
  protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
  {
    PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
  }
}