import os

def get_app_class(template):
    class App(template):
        def F_main(self):
            if len(self.argv) == 1:
                directory = "."
            else:
                directory = self.argv[1]

            try:
                for file in os.listdir(directory):
                    print(file)
            except OSError as e:
                print(str(e))

            self.exit()

    return App