More programmatic access to error locations in the traceback module

Feature or enhancement

I'd like for the traceback module to have a more programmatic way to access the fine-grained error locations that are printed in tracebacks starting in Python 3.11 (PEP 657).

Pitch

The new fine-grained error information in tracebacks is nice. But I'd like to be able to write a custom traceback printer that uses this information and prints it in a different way (I'd like to highlight the characters in the lines of source rather than having ASCII characters under them).

The logic for getting the locations of the printed fine-grained information is present in the traceback module, but unfortunately, it's only present inside of the format_frame_summary() method, which returns a string. That means that to access the information, I have to parse the string.

It would be convenient if the logic in that method were separated out into a separate method that returned the column numbers, so that it could be called from a superclass. I would be fine if this method is private, so that it wouldn't strictly speaking add a new API or hard-code the existing traceback information into the API.

Previous discussion

I haven't followed the discussions on PEP 657 so I don't know if this has been discussed previously. I don't see any mention of the traceback module in the PEP.

从 Lib/traceback.py 中的 format_frame_summary() 开始，这里描述了现有的细粒度 traceback 位置逻辑。确定如何分离该逻辑，以便在不解析返回字符串的情况下，为自定义 traceback 格式化提供列号。完成的标准是调用方可以通过程序访问这些位置，同时保留现有的 traceback 输出。