This is based on previous discussions of possible ways of matching all remaining items during destructuring but without iterating of remaining final items. This is not exactly a direct replacement for that idea though, and skipping iteration of final items might or might not be part of the goal.
In this proposal, the ellipsis (...) can be used in the expression on the left side of the equals sign in destructuring anywhere that `*<varname>` can appear and has approximately the same meaning. The difference is that when the ellipsis is used, the matched items are not stored in variables. This can be useful when the matched data might be very large. ..., last_one = <expression> a, ..., z = <expression> first_one, ... = <expression> Additionally, when the ellipsis comes last and the data is being retrieved by iterating, stop retrieving items since that might be expensive and we know that we will not use them. Alternative A: Still iterate over items when the ellipsis comes last (for side effects) but introduce a new `final_elipsis` object that is used to stop iteration. The negation of `ellipsis` (e.g. `-...`) could return `final_ellipsis` in that case. Alternative B: Still iterate over items when the ellipsis comes last (for side effects) and don't provide any new means of skipping iteration over final items. The programmer can use islice to achieve that. _______________________________________________ Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-le...@python.org https://mail.python.org/mailman3/lists/python-ideas.python.org/ Message archived at https://mail.python.org/archives/list/python-ideas@python.org/message/QPMFXOOHKQJ6YFM35SJXZMANBQTRZ3FY/ Code of Conduct: http://python.org/psf/codeofconduct/
