On 4 Jun 2008, at 09:45, Raymond Hettinger wrote:
In the case of intersection and intersection_update, if the inputs are sets or dicts, then they should be processed smallest to largest. If the inputs are not sets or dicts, then process them in input order.
The other six cases should also be processed in-order (left-to-right).
Given that A - X - Y - Z is the same as (A-X) & (A-Y) & (A-Z) If it is a significant optimization to intersect sets from smallest to largest (as opposed to just starting with the smallest one and then intersecting from left to right), then should the same idea be applied to difference, except that obviously you start with the leftmost one and sort the others from largest to smallest? (I am *not* proposing to compute A-X, A-Y, ... and then intersect them!) -- Arnaud