数据 marshal 操作支持

这些例程允许 C 代码处理与 marshal 模块所用相同数据格式的序列化对象。 其中有些函数可用来将数据写入这种序列化格式，另一些函数则可用来读取并恢复数据。 用于存储 marshal 数据的文件必须以二进制模式打开。

数字值在存储时会将最低位字节放在开头。

The module supports two versions of the data format: version 0 is the historical version, version 1 (new in Python 2.4) shares interned strings in the file, and upon unmarshalling. Version 2 (new in Python 2.5) uses a binary format for floating point numbers. Py_MARSHAL_VERSION indicates the current file format (currently 2).

void PyMarshal_WriteLongToFile(long value, FILE *file, int version)

Marshal a long integer, value, to file. This will only write the least-significant 32 bits of value; regardless of the size of the native long type.

在 2.4 版更改: version indicates the file format.

void PyMarshal_WriteObjectToFile(PyObject *value, FILE *file, int version)

Marshal a Python object, value, to file.

在 2.4 版更改: version indicates the file format.

PyObject* PyMarshal_WriteObjectToString(PyObject *value, int version)

Return value: New reference.

Return a string object containing the marshalled representation of value.

在 2.4 版更改: version indicates the file format.

以下函数允许读取并恢复存储为 marshal 格式的值。

XXX What about error detection? It appears that reading past the end of the file will always result in a negative numeric value (where that’s relevant), but it’s not clear that negative values won’t be handled properly when there’s no error. What’s the right way to tell? Should only non-negative values be written using these routines?

long PyMarshal_ReadLongFromFile(FILE *file)

从打开用于读取的 FILE* 的对应数据流返回一个 C long。 使用此函数只能读取 32 位的值，无论本机 long 类型的长度如何。

int PyMarshal_ReadShortFromFile(FILE *file)

从打开用于读取的 FILE* 的对应数据流返回一个 C short。 使用此函数只能读取 16 位的值，无论本机 short 的长度如何。

PyObject* PyMarshal_ReadObjectFromFile(FILE *file)

Return value: New reference.

Return a Python object from the data stream in a FILE* opened for reading. On error, sets the appropriate exception (EOFError or TypeError) and returns NULL.

PyObject* PyMarshal_ReadLastObjectFromFile(FILE *file)

Return value: New reference.

Return a Python object from the data stream in a FILE* opened for reading. Unlike PyMarshal_ReadObjectFromFile(), this function assumes that no further objects will be read from the file, allowing it to aggressively load file data into memory so that the de-serialization can operate from data in memory rather than reading a byte at a time from the file. Only use these variant if you are certain that you won’t be reading anything else from the file. On error, sets the appropriate exception (EOFError or TypeError) and returns NULL.

PyObject* PyMarshal_ReadObjectFromString(char *string, Py_ssize_t len)

Return value: New reference.

Return a Python object from the data stream in a character buffer containing len bytes pointed to by string. On error, sets the appropriate exception (EOFError or TypeError) and returns NULL.

在 2.5 版更改: This function used an int type for len. This might require changes in your code for properly supporting 64-bit systems.