On 8 March 2012 11:11, Sudip Bhattacharya <sud...@sudipb.com> wrote: >>>> s=(1,2,3) >>>> s=s+(4,5,6) >>>>s > (1,2,3,4,5,6) > > The tuple has changed.
No, the tuple hasn't changed. That's a *new* tuple. Consider: Python 2.7.2 (default, Jun 12 2011, 14:24:46) [MSC v.1500 64 bit (AMD64)] on win32 Type "copyright", "credits" or "license()" for more information. >>> s=(1,2,3) >>> id(s) 44137280L >>> s=s+(4,5,6) >>> id(s) 34277416L >>> l=[1,2,3] >>> id(l) 44152072L >>> l.extend([4,5,6]) >>> id(l) 44152072L >>> l [1, 2, 3, 4, 5, 6] >>> l=l+[7,8,9] >>> id(l) 44150856L >>> l [1, 2, 3, 4, 5, 6, 7, 8, 9] >>> So, as you can see, in the case of the tuple, the addition actually creates a *new* tuple (different id) that consists of the members of the 2 input tuples, whereas in the case of the list, since the list is mutable, the same list (same id) is *changed* when you add another list to it. Walter _______________________________________________ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
