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diff --git a/Doc/c-api/file.rst b/Doc/c-api/file.rst new file mode 100644 index 0000000..f08a155 --- /dev/null +++ b/Doc/c-api/file.rst @@ -0,0 +1,123 @@ +.. highlightlang:: c + +.. _fileobjects: + +File Objects +------------ + +.. index:: object: file + +Python's built-in file objects are implemented entirely on the :ctype:`FILE\*` +support from the C standard library. This is an implementation detail and may +change in future releases of Python. + + +.. ctype:: PyFileObject + + This subtype of :ctype:`PyObject` represents a Python file object. + + +.. cvar:: PyTypeObject PyFile_Type + + .. index:: single: FileType (in module types) + + This instance of :ctype:`PyTypeObject` represents the Python file type. This is + exposed to Python programs as ``file`` and ``types.FileType``. + + +.. cfunction:: int PyFile_Check(PyObject *p) + + Return true if its argument is a :ctype:`PyFileObject` or a subtype of + :ctype:`PyFileObject`. + + +.. cfunction:: int PyFile_CheckExact(PyObject *p) + + Return true if its argument is a :ctype:`PyFileObject`, but not a subtype of + :ctype:`PyFileObject`. + + +.. cfunction:: PyFile_FromFd(int fd, char *name, char *mode, int buffering, char *encoding, char *newline, int closefd) + + Create a new :ctype:`PyFileObject` from the file descriptor of an already + opened file *fd*. The arguments *name*, *encoding* and *newline* can be + *NULL* to use the defaults; *buffering* can be *-1* to use the default. + Return *NULL* on failure. + + .. warning:: + + Take care when you are mixing streams and descriptors! For more + information, see `the GNU C Library docs + <http://www.gnu.org/software/libc/manual/html_node/Stream_002fDescriptor-Precautions.html#Stream_002fDescriptor-Precautions>`_. + + +.. cfunction:: int PyObject_AsFileDescriptor(PyObject *p) + + Return the file descriptor associated with *p* as an :ctype:`int`. If the + object is an integer, its value is returned. If not, the + object's :meth:`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. + + +.. cfunction:: PyObject* PyFile_GetLine(PyObject *p, int n) + + .. index:: single: EOFError (built-in exception) + + 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 :meth:`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 :exc:`EOFError` is + raised if the end of the file is reached immediately. + + +.. cfunction:: PyObject* PyFile_Name(PyObject *p) + + Return the name of the file specified by *p* as a string object. + + +.. cfunction:: void PyFile_SetBufSize(PyFileObject *p, int n) + + .. index:: single: setvbuf() + + Available on systems with :cfunc:`setvbuf` only. This should only be called + immediately after file object creation. + + +.. cfunction:: int PyFile_SetEncoding(PyFileObject *p, const char *enc) + + Set the file's encoding for Unicode output to *enc*. Return 1 on success and 0 + on failure. + + +.. cfunction:: int PyFile_SoftSpace(PyObject *p, int newflag) + + .. index:: single: softspace (file attribute) + + This function exists for internal use by the interpreter. Set the + :attr:`softspace` attribute of *p* to *newflag* and return the previous value. + *p* does not have to be a file object for this function to work properly; any + object is supported (thought its only interesting if the :attr:`softspace` + attribute can be set). This function clears any errors, and will return ``0`` + as the previous value if the attribute either does not exist or if there were + errors in retrieving it. There is no way to detect errors from this function, + but doing so should not be needed. + + +.. cfunction:: int PyFile_WriteObject(PyObject *obj, PyObject *p, int flags) + + .. index:: single: Py_PRINT_RAW + + Write object *obj* to file object *p*. The only supported flag for *flags* is + :const:`Py_PRINT_RAW`; if given, the :func:`str` of the object is written + instead of the :func:`repr`. Return ``0`` on success or ``-1`` on failure; the + appropriate exception will be set. + + +.. cfunction:: int PyFile_WriteString(const char *s, PyObject *p) + + Write string *s* to file object *p*. Return ``0`` on success or ``-1`` on + failure; the appropriate exception will be set. |