[REQUEST] PEP657 error code ranges in tracebacks

Python 3.11 implements code position ranges in tracebacks.

from rich.traceback import install
install(show_locals=True)
data = [
    {
        "person": {
            "friends": [
                {"name": "Sally",
                "age": 32},
                {"name": "Yuri",
                "age": 43}
            ],
            "location": "Warsaw, Poland"
        }
    }
]

print(data[0]["person"]["friends"][2]["name"])

The default exception handler will print the position of the offending error in the traceback:

Traceback (most recent call last):
  File "/Users/anthonyshaw/projects/python-3.11-demos/error_messages.py", line 15, in <module>
    print(data[0]["person"]["friends"][2]["name"])
          ~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^
IndexError: list index out of range

Rich does not use this data (but still looks very pretty)

IT would be great to get the trace messages with arrows.

[pradyunsg]

This is very much a drive-by comment: I wonder if there’s Unicode characters that could be used for this.

[tonybaloney]

Note: TracebackException now has the offset and end_offset attributes which expose the information needed to print the arrows.

https://github.com/python/cpython/blob/3.11/Lib/traceback.py#L852-L864