On Wednesday, November 18, 2015 at 7:15:05 PM UTC-5, Chris Angelico wrote: > On Thu, Nov 19, 2015 at 11:02 AM, Ian Kelly <ian.g.ke...@gmail.com> wrote: > > On Wed, Nov 18, 2015 at 4:22 PM, Chris Angelico <ros...@gmail.com> wrote: > >> On Thu, Nov 19, 2015 at 10:14 AM, BartC <b...@freeuk.com> wrote: > >>> So, looking at some source code, a default value for certain types is only > >>> certain to be that value for the very first call of that function? > >> > >> On the contrary, it is certain always to be that exact object. > > > > "Certain" may be a bit overly strong. > > > >>>> def f(x=42): > > ... return x > > ... > >>>> f() > > 42 > >>>> f.__defaults__ = (43,) > >>>> f() > > 43 > > I'll raise you one. > > >>> def f(x=42): > ... return x > ... > >>> f() > 42 > >>> import ctypes > >>> ctypes.c_int.from_address(id(43)+ ctypes.sizeof(ctypes.c_size_t) + > >>> ctypes.sizeof(ctypes.c_voidp)).value=42 > >>> f.__defaults__ = (43,) > >>> f() > 42 > >>> > > Nothing is certain in Python. And two wrongs can make a... hmm... no, > this is not a right. It is not a privilege either. It is a dastardly > trick played on people's minds. > > ChrisA
After I try with list1 = eList(12, [2]) and list1 = eList(12) it gives me new surprises. Even though I delete list1, the subsequent list1 = eList(12) will remember the number of '12' of the previous sequence. This is my new question: What does 'del' do? It does not look like a thorough list deletion from the effect. Thanks, ..................... list1 = eList(12, [2]) list1 Out[57]: [2, 12] list1 = eList(12) list1 Out[59]: [12, 12, 12] list1 = eList(12, [2]) list1 Out[61]: [2, 12] list1 = eList(12, [2]) list1 Out[63]: [2, 12] list1 = eList(12, [2]) list1 Out[65]: [2, 12] list1 = eList(12) list1 Out[67]: [12, 12, 12, 12] list1 = eList(12) list1 Out[69]: [12, 12, 12, 12, 12] list1 = eList(12, [2]) list1 Out[71]: [2, 12] list1 = eList(12) list1 Out[73]: [12, 12, 12, 12, 12, 12] del list1 list1 = eList(12, [2]) list1 = eList(12) list1 Out[77]: [12, 12, 12, 12, 12, 12, 12] -- https://mail.python.org/mailman/listinfo/python-list
