Terry J. Reedy <[email protected]> added the comment:
Should we mention that the 4 attributes are also available as a 4-tuple that is
the 2nd item of the args tuple, after the message? Doing so will help when
illustrating the following.
For syntax errors in f-string fields, the expanded doc is still
incomplete/erroneous. The text attribute is the replacement expression wrapped
in parentheses (or with {} replaced by ()), with \n added; the column is the
(1-based) offset within that constructed source.
>>> try:
compile("f'Bad {a b} field'", '', 'exec')
except SyntaxError as e:
print(e.args)
('f-string: invalid syntax', ('', 1, 4, '(a b)\n'))
This was brought to my attention a week or so ago because IDLE still thinks
that 4 refers to the 'a' of 'Bad' and marks it is the error location. I had
to deduce the rule from examples.
Whether for this issue or a new one, I am thinking of something like the
following.
---
For syntax error instances, the args attribute is (error-message,
details-tuple). The str returns only the error message. For convenience, the
four details are also available as separate attributes.
<new list as is>
For errors in f-string fields, the message is prefixed by "f-string:" and the
offset is the offset in a text constructed from the replacement expression.
For example, compiling f'Bad {a b} field' results in the following args
attribute: ('f-string: invalid syntax', ('', 1, 4, '(a b)\n')).
I think it okay to require the reader to match '{a b}' and '(a b)\n' to deduce
the transformation rule. Messages other than 'invalid syntax', like 'closing
parenthesis ...' get the same prefix. Anything Python specific can be labelled
as such.
----------
nosy: -miss-islington
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<https://bugs.python.org/issue43705>
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