from contextlib import contextmanager

@contextmanager
def open_file(file_path, mode):
    file = open(file_path, mode)
    try:
        yield file  # 提供檔案資源
    finally:
        file.close()  # 確保檔案關閉
        print(f"檔案 {file_path} 已關閉")

# 使用自訂上下文管理器
with open_file("example.txt", "w") as f:
    f.write("這是一個測試檔案\n")