檔案物件 (File Objects)
***********************

這些 API 是用於內建檔案物件的 Python 2 C API 的最小模擬 (minimal
emulation)，它過去依賴於 C 標準函式庫對於緩衝 I/O (FILE*) 的支援。在
Python 3 中，檔案和串流使用新的 "io" 模組，它在操作系統的低階無緩衝
I/O 上定義了多個層級。下面描述的函式是這些新 API 的便捷 C 包裝器，主要
用於直譯器中的內部錯誤報告；建議第三方程式碼改為存取 "io" API。

PyObject *PyFile_FromFd(int fd, const char *name, const char *mode, int buffering, const char *encoding, const char *errors, const char *newline, int closefd)
    *回傳值：新的參照。** Part of the Stable ABI.*

   Create a Python file object from the file descriptor of an already
   opened file *fd*.  The arguments *name*, *encoding*, *errors* and
   *newline* can be "NULL" to use the defaults; *buffering* can be
   *-1* to use the default. *name* is ignored and kept for backward
   compatibility. Return "NULL" on failure. For a more comprehensive
   description of the arguments, please refer to the "io.open()"
   function documentation.

   警告:

     由於 Python 串流有自己的緩衝層，將它們與操作系統層級檔案描述器混
     合使用會產生各種問題（例如資料的排序不符合預期）。

   在 3.2 版的變更: 忽略 *name* 屬性。

int PyObject_AsFileDescriptor(PyObject *p)
    * Part of the Stable ABI.*

   回傳與 *p* 關聯的檔案描述器作為 int。如果物件是整數，則回傳其值。如
   果不是整數，則呼叫物件的 "fileno()" 方法（如果存在）；該方法必須回
   傳一個整數，它作為檔案描述器值回傳。設定例外並在失敗時回傳 "-1"。

PyObject *PyFile_GetLine(PyObject *p, int n)
    *回傳值：新的參照。** Part of the Stable ABI.*

   Equivalent to "p.readline([n])", this function reads one line from
   the object *p*.  *p* may be a file object or any object with a
   "readline()" method.  If *n* is "0", exactly one line is read,
   regardless of the length of the line.  If *n* is greater than "0",
   no more than *n* bytes will be read from the file; a partial line
   can be returned.  In both cases, an empty string is returned if the
   end of the file is reached immediately.  If *n* is less than "0",
   however, one line is read regardless of length, but "EOFError" is
   raised if the end of the file is reached immediately.

int PyFile_SetOpenCodeHook(Py_OpenCodeHookFunction handler)

   覆蓋 "io.open_code()" 的正常行為以透過提供的處理程式 (handler) 傳遞
   其參數。

   The *handler* is a function of type:

   typedef PyObject *(*Py_OpenCodeHookFunction)(PyObject*, void*)

      Equivalent of PyObject *(*)(PyObject *path, void *userData),
      where *path* is guaranteed to be "PyUnicodeObject".

   *userData* 指標被傳遞到掛鉤函式 (hook function) 中。由於可能會從不
   同的執行環境 (runtime) 呼叫掛鉤函式，因此該指標不應直接指向 Python
   狀態。

   由於此掛鉤函式是在導入期間有意使用的，因此請避免在其執行期間導入新
   模組，除非它們已知有被凍結或在 "sys.modules" 中可用。

   Once a hook has been set, it cannot be removed or replaced, and
   later calls to "PyFile_SetOpenCodeHook()" will fail. On failure,
   the function returns -1 and sets an exception if the interpreter
   has been initialized.

   在 "Py_Initialize()" 之前呼叫此函式是安全的。

   不帶引數地引發一個稽核事件 (auditing event) "setopencodehook"。

   在 3.8 版新加入.

int PyFile_WriteObject(PyObject *obj, PyObject *p, int flags)
    * Part of the Stable ABI.*

   Write object *obj* to file object *p*.  The only supported flag for
   *flags* is "Py_PRINT_RAW"; if given, the "str()" of the object is
   written instead of the "repr()".  Return "0" on success or "-1" on
   failure; the appropriate exception will be set.

int PyFile_WriteString(const char *s, PyObject *p)
    * Part of the Stable ABI.*

   寫入字串 *s* 到 檔案物件 *p*。當成功時回傳 0，而當失敗時回傳 -1，並
   會設定合適的例外狀況。
