New submission from Nikita Sobolev <m...@sobolevn.me>:
While working on https://github.com/python/cpython/pull/30058 I've noticed that
`Positions` namedtuple is kinda strange, source:
https://github.com/python/cpython/blame/8c2fd09f365e082cfceb29afdf38953cdd670946/Lib/dis.py#L204-L213
Why?
1. It is not used. `grep` shows that:
```
ยป ag Positions .
Misc/HISTORY
21894: treated as being relative to the end of the input string. Positions
Objects/codeobject.c
1021:static PyTypeObject PositionsIterator = {
1067: positionsiterator* pi =
(positionsiterator*)PyType_GenericAlloc(&PositionsIterator, 0);
Mac/PythonLauncher/English.lproj/MainMenu.nib/info.nib
7: <key>IBEditorPositions</key>
Lib/dis.py
204:Positions = collections.namedtuple(
205: 'Positions',
239:_Instruction.positions.__doc__ = "dis.Positions object holding the span of
source code covered by this instruction"
259: positions - Optional dis.Positions object holding the span of
source code
Lib/test/test_compile.py
1013:class TestSourcePositions(unittest.TestCase):
Doc/library/re.rst
1579:Finding all Adverbs and their Positions
```
2. Commenting it out does not make `test_dis` to fail (again, because it does
not seem to be used)
3. It is documented (in docstrings only, not in `dis.rst`) that
`Instruction.positions` is `dis.Positions`, but this is not true. Because
`Instruction` is created as:
```python
co_positions = co_positions or iter(())
try:
positions = next(co_positions)
except StopIteration:
positions = None
Instruction(positions=positions)
```
So, it is at best is `tuple | None`. Never `Positions`.
What to do with it?
1. Should it be removed as unused, undocumented, and unreleased?
2. Should it be used as documented? Here:
https://github.com/python/cpython/blame/8c2fd09f365e082cfceb29afdf38953cdd670946/Lib/dis.py#L453-L455
3. Any other ideas?
In my opinion, it is not required, because we already have
`codeobject.co_positions` which is pretty much the same thing:
https://docs.python.org/3.11/reference/datamodel.html?highlight=co_positions#codeobject.co_positions
I would like to work on it after a final decision is made :)
----------
components: Library (Lib)
messages: 410855
nosy: BTaskaya, pablogsal, sobolevn
priority: normal
severity: normal
status: open
title: Why do we need `dis.Positions`?
type: behavior
versions: Python 3.11
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Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue46422>
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