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Add the attribute that describe which operation cause NameError in NameError object #140779
Closed as duplicate
Description
Feature or enhancement
Proposal:
>>> del next
Traceback (most recent call last):
File "<python-input-0>", line 1, in <module>
del next
^^^^
NameError: name 'next' is not defined. Did you mean: 'anext'?
>>> del anext
Traceback (most recent call last):
File "<python-input-1>", line 1, in <module>
del anext
^^^^^
NameError: name 'anext' is not defined. Did you mean: 'next'?As you see, the two suggestions played football with you about which name was right (508 loop detected).
The reason is that now the code in _compute_suggestion_error anyway add f_builtins when suggest for NameError :
https://github.com/python/cpython/blob/main/Lib/traceback.py#L1670-L1682
assert isinstance(exc_value, NameError)
# find most recent frame
if tb is None:
return None
while tb.tb_next is not None:
tb = tb.tb_next
frame = tb.tb_frame
d = (
list(frame.f_locals)
+ list(frame.f_globals)
+ list(frame.f_builtins)
)
d = [x for x in d if isinstance(x, str)]
If we can add the attribute in NameError (e.g. "op") to describe which operation cause the NameError, the suggestion will be more exactly:
assert isinstance(exc_value, NameError)
# find most recent frame
if tb is None:
return None
while tb.tb_next is not None:
tb = tb.tb_next
frame = tb.tb_frame
if getattr(exc_value, "op", "getting") == "deleting":
d = (list(frame.f_locals)
+ list(frame.f_globals))
else:
d = (
list(frame.f_locals)
+ list(frame.f_globals)
+ list(frame.f_builtins)
)
d = [x for x in d if isinstance(x, str)]
By this way, the suggestion on NameError caused by deleting a variable won't possibly be a builtins name that user hasn't redefined it.
Has this already been discussed elsewhere?
This is a minor feature, which does not need previous discussion elsewhere
Links to previous discussion of this feature:
No response
Activity
picnixz commentedon Oct 30, 2025
I will close this one as a duplicate of #138890 because the use case is only for the special case of
del. Also, I don't think this issue should have been opened because the DPO thread did not receive much support in the first place.I personally don't want to expose the operation type in
NameError. An alternative would be a subclass ofNameErrorbut it also has caveats that I'm not willing to support.