Nick Coghlan <ncogh...@gmail.com> added the comment:
https://github.com/ncoghlan/cpython/pull/9/commits/54940a3817df3046da3f9c51d4d426a73b2ec786 implements Brandt's suggestion of disallowing NULL keys in MatchMapping and instead passing in an explicit "rest" identifier to capture the extra keys. This did require moving to a multi-branch pattern definition in the grammar, similar to class patterns, in order to enforce the separating comma when both ordinary key:pattern pairs and a double-star target are present. I think it's a nice ergonomic improvement on the AST node itself though, as it makes it trivial to check if a mapping patterns captures extra keys or not (vs the relatively non-obvious check to see if the last key is NULL/None). That just leaves updating the unparser to handle the new node types. Capturing the latest node definitions from the draft PR: pattern = MatchAlways | MatchValue(expr value) | MatchSingleton(constant value) | MatchSequence(pattern* patterns) | MatchMapping(expr* keys, pattern* patterns, identifier? rest) | MatchClass(expr cls, pattern* patterns, identifier* kwd_attrs, pattern* kwd_patterns) | MatchStar(identifier? target) -- The optional "rest" MatchMapping parameter handles capturing extra mapping keys | MatchAs(pattern? pattern, identifier target) | MatchOr(pattern* patterns) attributes (int lineno, int col_offset, int end_lineno, int end_col_offset) ---------- _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue43892> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
