def METHOD_NAME(self):
    """
    Browse the file and calculate slit lenght upon loading
    """
    path_str = self.chooseFile()
    if not path_str:
        return
    loader = Loader()
    try:
        data = loader.load(path_str)
        data = data[0]
    # Can return multiple exceptions - gather them all under one umbrella and complain
    except Exception as ex:
        logging.error(ex)
        return
    self.data_file.setText(os.path.basename(path_str))
    self.calculateSlitSize(data)