> Then how will modules that customizes traceback presentation, such as
idlelib, be able to get the 4-tuple for a particular traceback entry?
From the exception, you can get the code object and from the code
object the extra information using
the Python API:
Example:
>>> try:
... 1/0
... except Exception as e:
... f = e
>>> list(f.__traceback__.tb_frame.f_code.co_positions())
[(1, 4, 1, 8), (2, 2, 3, 4), (2, 2, 5, 6), (2, 2, 3, 6), (2, 2, 3, 6),
(2, 4, 3, 8), (2, 4, 3, 8), (None, 2, 3, 6), (3, 4, 1, 8), (3, 3, 8,
17), (3, 4, 1, 8), (3, 4, 1, 8), (3, 4, 1, 8), (3, 4, 1, 8), (4, 4, 7,
8), (4, 4, 3, 4), (4, 4, 3, 8), (4, 4, 3, 8), (4, 4, 3, 8), (4, 4, 3,
8), (4, 4, 3, 8), (4, 4, 3, 8), (None, 4, 3, 8), (None, 4, 3, 8), (None,
4, 3, 8), (None, 4, 3, 8), (None, 4, 3, 8), (3, 4, 3, 8)]
Ah, co_positions is an access method, corresponding to the current (also
undocumented) co_lines. There will be no direct access to the
position-table as it will be kept private and subject to change. The
obvious first question: why 28 items and what does the index mean?
When I compile the above with 3.10.0b3, there are 29 bytecodes, so I am
guessing your branch has 28 and that the first number in the tuple is
the line number. But how would one know which '2' entry corresponds to
the divide in '1/0'. And what do the rest of the tuple numbers mean? I
don't see anything like the (2,2, 2,4) I expect for '1/0'. To be
documented, as you say below.
This is equivalent (and more efficient) to have this information in the
traceback itself (as it would have been duplicated and would require
more changes).
Understood and agreed.
We would document this a bit better with some examples. And we will make
sure to add docs about this for sure :)
--
Terry Jan Reedy
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