PEP 572: TargetScopeError->SyntaxError, other SyntaxError adjustments#1140
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ncoghlan merged 5 commits intopython:masterfrom Aug 14, 2019
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- clarify rationale for the extra TargetScopeError cases (we don't want current CPython implementation details to implicitly leak into the "do what CPython does" de facto language specification) - broaden one of the error cases to handle the fact that CPython's symbol table analysis for a comprehension involves two different scopes and hence makes it difficult to detect when the target of a named expression in the iterable expression gets re-used as an iteration variable in the comprehension
gvanrossum
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Aug 5, 2019
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Thanks for doing this! I have some nits.
Also, I wonder if we could smuggle a reference to "walrus operator" into the abstract, to aid search engines?
- drop TargetScopeError from the PEP in favour of SyntaxError - use the same marker for invalid constructs as the rest of the PEP - clarify that the ban on named expressions in comprehension iterable expressions is consistent (rather than only being on the first one) - provide a bit more detail on the CPython constraint that keeps us from implementing the "only complain on name conflicts" rule for iterable expressions - add a new note on naming that covers both the informal name and the internal name in the reference implementation
gvanrossum
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Aug 10, 2019
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OK, I am happy now! Not sure if @tim-one or @Rosuav want to chime in still?
CC: @emilyemorehouse
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All good from my end! |
ncoghlan
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warsaw
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TargetScopeErrorto a plainSyntaxErroras per referenced python-dev discussion
want current CPython implementation details to implicitly leak into
the "do what CPython does" de facto language specification)
symbol table analysis for a comprehension involves two different
scopes and hence makes it difficult to detect when the target of
a named expression in the iterable expression gets re-used as an
iteration variable in the comprehension