python - 什么是 SwigPyObject 对象？

Question

当我尝试使用

保存自定义对象时出现错误

以 open(path + '/' + 'my_object.pickle', 'wb') 作为句柄:
pickle.dump(my_class_instance, handle, protocol=pickle.HIGHEST_PROTOCOL)

错误信息是:

TypeError: can't pickle SwigPyObject objects

我的第一个问题是:什么是 SwigPyObject 对象？，因此我可以尝试找出错误的来源。

Answer 1

什么是 SWIG？

Simplified Wrapper and Interface Generator (SWIG) 是一种开源软件工具，用于将用 C 或 C++ 编写的库与脚本语言(如 Python)连接起来。 SWIG 的一个众所周知的替代品是 Boost。 Boost Library旨在完成同样的事情。

您使用 SWIG 创建一个用 C/C++ 开发的 Python 库(用于与现有 C/C++ 库的互操作性或提高性能等)。

引用SWIG documentation :

To build Python extension modules, SWIG uses a layered approach in which parts of the extension module are defined in C and other parts are defined in Python. The C layer contains low-level wrappers whereas Python code is used to define high-level features.

This layered approach recognizes the fact that certain aspects of extension building are better accomplished in each language (instead of trying to do everything in C or C++). Furthermore, by generating code in both languages, you get a lot more flexibility since you can enhance the extension module with support code in either language.

什么是 SwigPyObject 对象？

SwigPyObject 对象在 SWIG documentation 的主题“有关 Python 类接口(interface)的更多详细信息”中进行了描述。 .

这个对象是一个实现细节。它由以下 C 结构定义:

typedef struct {
    PyObject_HEAD
    void *ptr;
    swig_type_info *ty;
    int own;
    PyObject *next;
    PyObject *dict;
} SwigPyObject;

SwigPyObject 对象存储 C++ 对象的实例:

When -builtin is used, the pure python layer is stripped off. Each wrapped class is turned into a new python built-in type which inherits from SwigPyObject, and SwigPyObject instances are returned directly from the wrapped methods.

pickle 文件

您的 pickle 文件中包含的数据包含一个 SwigPyObject 对象，但您的解释器不知道如何反序列化它。您需要检查您的 virtualenv 是否包含提供您的 pickle 对象的 Python/C++ 库。