# File lib/win32/file.rb, line 921
   def readonly=(bool)
      attributes = GetFileAttributes(self.path)
      
      if attributes == INVALID_FILE_ATTRIBUTES
         raise ArgumentError, get_last_error
      end
      
      if bool
         attributes |= FILE_ATTRIBUTE_READONLY;
      else
         attributes &= ~FILE_ATTRIBUTE_READONLY;
      end
      
      if SetFileAttributes(self.path, attributes) == 0
         raise ArgumentError, get_last_error
      end

      self
   end