Python C API：如何获取异常的字符串表示形式？ [英] Python C API: how to get string representation of exception?

问题描述

如果我愿意（例如）

 open("/snafu/fnord")

（在文件中不存在），我得到了回溯和消息

in Python (and the file does not exist), I get a traceback and the message

 IOError: [Errno 2] No such file or directory: '/snafu/fnord'

我想使用Python的C API（即，嵌入在C程序中的Python解释器）获得上述字符串。我需要它作为字符串，而不是输出到控制台。

I would like to get the above string with Python's C API (i.e., a Python interpreter embedded in a C program). I need it as a string, not output to the console.

使用 PyErr_Fetch（）可以得到类型异常的对象和值。对于上面的示例，该值是一个元组：

With PyErr_Fetch() I can get the type object of the exception and the value. For the above example, the value is a tuple:

 (2, 'No such file or directory', '/snafu/fnord')

从我从 PyErr_Fetch获得的信息中是否有简便的方法（）到Python解释器显示的字符串？ （一个不涉及自己为每种异常类型构造此类字符串的字符串。）

Is there an easy way from the information I get from PyErr_Fetch() to the string the Python interpreter shows? (One that does not involve to construct such strings for each exception type yourself.)

推荐答案

我认为Python异常是通过以下方式打印的：在异常实例上运行 str（），它将返回您感兴趣的格式化字符串。您可以通过调用 PyObject_Str（） 方法，如下所述：

I think that Python exceptions are printed by running "str()" on the exception instance, which will return the formatted string you're interested in. You can get this from C by calling the PyObject_Str() method described here:

https://docs.python.org/c-api /object.html

祝你好运！

更新：我有些困惑，为什么 PyErr_Fetch（）返回给您的第二个元素是字符串。我的猜测是，您收到一个未规范化的异常，需要调用 PyErr_NormalizeException（）将该元组变成真实的异常，该异常可以将自身格式化为类似于您想要它。

Update: I'm a bit confused why the second element being returned to you by PyErr_Fetch() is a string. My guess is that you are receiving an "unnormalized exception" and need to call PyErr_NormalizeException() to turn that tuple into a "real" Exception that can format itself as a string like you want it to.

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