On Wed, 2 Sep 2015 08:01 pm, Antoon Pardon wrote: > >>>> a = [1, 2, 3, 4, 5] >>>> b = 1 >>>> b, a[b] = a[b], b >>>> a > [1, 2, 1, 4, 5]
Equivalent to: temp1 = a[b] # a[1] == 2 temp2 = b # 1 b = temp1 # b = 2 a[b] = temp2 # a[2] = 1 Or using a queue (FIFO) rather than temp variables: push a[b] push b b = pop a[b] = pop which seems sensible to me. The right hand side of the assignment is evaluated left-to-right, and then the assignments are made, from left-to-right. Which I believe matches the documented order. >>>> a = [1, 2, 3, 4, 5] >>>> b = 1 >>>> a[b], b = b, a[b] >>>> a > [1, 1, 3, 4, 5] Likewise: temp1 = b # 1 temp2 = a[b] # a[1] == 2 a[b] = temp1 # a[1] = 1 b = temp2 # b = 2 > I think I understand how it gets these results > but I'm not really happy with them. I think python > should give the second result in both cases. Apart from breaking backwards compatibility, how would you implement such a thing? A simple left-to-right assignment rule is easy to implement and easy to understand even when the targets depend on each other. -- Steven -- https://mail.python.org/mailman/listinfo/python-list
