Colin J. Williams wrote: > Neil Cerutti wrote: >> On Jan 15, 2008 10:10 AM, <[EMAIL PROTECTED]> wrote: >>> I've noticed that I can update() a set with a list but I can't extend a set >>> with a list using the |= assignment operator. >>> >>> >>> s = set() >>> >>> s.update([1,2,3]) >>> >>> s >>> set([1, 2, 3]) >>> >>> s |= [4,5,6] >>> Traceback (most recent call last): >>> File "<stdin>", line 1, in <module> >>> TypeError: unsupported operand type(s) for |=: 'set' and 'list' >>> >>> s |= set([4,5,6]) >>> >>> s >>> set([1, 2, 3, 4, 5, 6]) >>> >>> Why is that? Doesn't the |= operator essentially map to an update() call? >> No, according to 3.7 Set Types, s | t maps to s.union(t). >> > If the RHS is a set then it works OK: > > *** Python 2.5.1 (r251:54863, Apr 18 > 2007, 08:51:08) [MSC v.1310 32 bit > (Intel)] on win32. *** >>>> import sets >>>> s1= sets.Set([2, 4, 5]) > Set([2, 4, 5]) >>>> s1= sets.Set([2, 4, 5]) >>>> s2= sets.Set([4, 5, 6]) >>>> s1|s2 > Set([2, 4, 5, 6]) >>>> s1|=s2 >>>> s1 > Set([2, 4, 5, 6]) > > It could be modified to handle any > iterable on the RHS. > > Colin W. >
I'm sorry, there appears to be a bug: # tSet.py import sets s1= sets.Set([1, 2, 3]) s1.union_update([3, 4,5]) print(s1) s2= sets.Set([6, 7, 8]) s1 |+ s2 # This fails: exceptions.TypeError: bad operand type for unary +: 'Set' print s1 Colin W. -- http://mail.python.org/mailman/listinfo/python-list
