檔案（File）物件
****************

These APIs are a minimal emulation of the Python 2 C API for built-in
file objects, which used to rely on the buffered I/O ("FILE*") support
from the C standard library.  In Python 3, files and streams use the
new "io" module, which defines several layers over the low-level
unbuffered I/O of the operating system.  The functions described below
are convenience C wrappers over these new APIs, and meant mostly for
internal error reporting in the interpreter; third-party code is
advised to access the "io" APIs instead.

PyFile_FromFd(int fd, const char *name, const char *mode, int buffering, const char *encoding, const char *errors, const char *newline, int closefd)
    *Return value: New reference.*

   根据已打开文件 *fd* 的文件描述符创建一个 Python 文件对象。 参数
   *name*, *encoding*, *errors* 和 *newline* 可以为 "NULL" 表示使用默
   认值；*buffering* 可以为 *-1* 表示使用默认值。 *name* 会被忽略仅保
   留用于向下兼容。 失败时返回 "NULL"。 有关参数的更全面描述，请参阅
   "io.open()" 函数的文档。

   警告: Since Python streams have their own buffering layer, mixing
     them with OS-level file descriptors can produce various issues
     (such as unexpected ordering of data).

   3.2 版更變: 忽略 *name* 屬性。

int PyObject_AsFileDescriptor(PyObject *p)

   Return the file descriptor associated with *p* as an "int".  If the
   object is an integer, its value is returned.  If not, the object's
   "fileno()" method is called if it exists; the method must return an
   integer, which is returned as the file descriptor value.  Sets an
   exception and returns "-1" on failure.

PyObject* PyFile_GetLine(PyObject *p, int n)
    *Return value: New reference.*

   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)

   重载 "io.open_code()" 的正常行为，将其形参通过所提供的处理程序来传
   递。

   处理程序是一个类型为 "PyObject *(*)(PyObject *path, void
   *userData)" 的函数，其中 *path* 确保为 "PyUnicodeObject"。

   *userData* 指针会被传入钩子函数。 因于钩子函数可能由不同的运行时调
   用，该指针不应直接指向 Python 状态。

   鉴于这个钩子专门在导入期间使用的，请避免在新模块执行期间进行导入操
   作，除非已知它们为冻结状态或者是在 "sys.modules" 中可用。

   一旦钩子被设定，它就不能被移除或替换，之后对
   "PyFile_SetOpenCodeHook()" 的调用也将失败，如果解释器已经被初始化，
   函数将返回 -1 并设置一个异常。

   此函数可以安全地在 "Py_Initialize()" 之前调用。

   3.8 版新加入.

int PyFile_WriteObject(PyObject *obj, PyObject *p, int flags)

   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)

   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。
