Apologies to all, I didn't notice the [] around a. But the basic point remains that the list that he is appending to is the same list as b refers to, albeit indirectly. He is still "touching" the list. Although not directly modifying the list to which b refers, since it still only holds one member, the list to which a refers....
Alan Gauld Author of the Learn To Program website http://www.alan-g.me.uk/ ----- Original Message ---- > From: Andre Engels <andreeng...@gmail.com> > To: Alan Gauld <alan.ga...@btinternet.com> > Cc: tutor@python.org > Sent: Monday, 14 March, 2011 9:23:47 > Subject: Re: [Tutor] Static Variable in Functions > > On Mon, Mar 14, 2011 at 9:56 AM, Alan Gauld <alan.ga...@btinternet.com> wrote: > > "Yasar Arabaci" <yasar11...@gmail.com> wrote > > > >> >>> a=["a"] > >> >>> b=[a] > >> >>> a.append("c") > >> >>> b > >> [['a', 'c']] > >> > >> Apperantly, I can change something (which is mutable) inside a list > >> without even touching the list itself :) > > > > But the point is that you *are* touching the list. > > In this case you have two names referring to the same list. > > You can modify that list (because it is mutable) via either name, it > > makes no difference because they both refer to the same list. > > > > So a.append() is exactly the same operation as b.append() > > No, they are not the same list. b is (a name of) a list with one > element, that one element being the list (denoted by) a. That's not > the same as a itself. > > -- > André Engels, andreeng...@gmail.com > _______________________________________________ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
