文件对象¶
Python’s built-in file objects are implemented entirely on the FILE*
support from the C standard library. This is an implementation detail and may
change in future releases of Python.
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PyTypeObject
PyFile_Type¶ This instance of
PyTypeObjectrepresents the Python file type. This is exposed to Python programs asfileandtypes.FileType.
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int
PyFile_Check(PyObject *p)¶ Return true if its argument is a
PyFileObjector a subtype ofPyFileObject.在 2.2 版更改: Allowed subtypes to be accepted.
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int
PyFile_CheckExact(PyObject *p)¶ Return true if its argument is a
PyFileObject, but not a subtype ofPyFileObject.2.2 新版功能.
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PyObject*
PyFile_FromString(char *filename, char *mode)¶ - Return value: New reference.
On success, return a new file object that is opened on the file given by filename, with a file mode given by mode, where mode has the same semantics as the standard C routine
fopen(). On failure, return NULL.
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PyObject*
PyFile_FromFile(FILE *fp, char *name, char *mode, int (*close)(FILE*))¶ - Return value: New reference.
Create a new
PyFileObjectfrom the already-open standard C file pointer, fp. The function close will be called when the file should be closed. Return NULL and close the file using close on failure. close is optional and can be set to NULL.
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FILE*
PyFile_AsFile(PyObject *p)¶ Return the file object associated with p as a
FILE*.If the caller will ever use the returned
FILE*object while the GIL is released it must also call thePyFile_IncUseCount()andPyFile_DecUseCount()functions described below as appropriate.
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void
PyFile_IncUseCount(PyFileObject *p)¶ Increments the PyFileObject’s internal use count to indicate that the underlying
FILE*is being used. This prevents Python from calling f_close() on it from another thread. Callers of this must callPyFile_DecUseCount()when they are finished with theFILE*. Otherwise the file object will never be closed by Python.The GIL must be held while calling this function.
The suggested use is to call this after
PyFile_AsFile()and before you release the GIL:FILE *fp = PyFile_AsFile(p); PyFile_IncUseCount(p); /* ... */ Py_BEGIN_ALLOW_THREADS do_something(fp); Py_END_ALLOW_THREADS /* ... */ PyFile_DecUseCount(p);
2.6 新版功能.
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void
PyFile_DecUseCount(PyFileObject *p)¶ Decrements the PyFileObject’s internal unlocked_count member to indicate that the caller is done with its own use of the
FILE*. This may only be called to undo a prior call toPyFile_IncUseCount().The GIL must be held while calling this function (see the example above).
2.6 新版功能.
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PyObject*
PyFile_GetLine(PyObject *p, int n)¶ - Return value: New reference.
等价于
p.readline([n])，这个函数从对象 p 中读取一行。 p 可以是文件对象或具有readline()方法的任何对象。 如果 n 是0，则无论该行的长度如何，都会读取一行。 如果 n 大于``0``，则从文件中读取不超过 n 个字节；可以返回行的一部分。 在这两种情况下，如果立即到达文件末尾，则返回空字符串。 但是，如果 n 小于0，则无论长度如何都会读取一行，但是如果立即到达文件末尾，则引发EOFError。
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PyObject*
PyFile_Name(PyObject *p)¶ - Return value: Borrowed reference.
Return the name of the file specified by p as a string object.
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void
PyFile_SetBufSize(PyFileObject *p, int n)¶ Available on systems with
setvbuf()only. This should only be called immediately after file object creation.
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int
PyFile_SetEncoding(PyFileObject *p, const char *enc)¶ Set the file’s encoding for Unicode output to enc. Return
1on success and0on failure.2.3 新版功能.
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int
PyFile_SetEncodingAndErrors(PyFileObject *p, const char *enc, *errors)¶ Set the file’s encoding for Unicode output to enc, and its error mode to err. Return
1on success and0on failure.2.6 新版功能.
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int
PyFile_SoftSpace(PyObject *p, int newflag)¶ This function exists for internal use by the interpreter. Set the
softspaceattribute 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 thesoftspaceattribute can be set). This function clears any errors, and will return0as 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.