zip as iterator and bad/good practices

[jimages]

> On Jun 12, 2015, at 11:00 PM, Fabien <fabien.maussion at gmail.com> wrote:
> but that awful bug made me wonder: is it a bad practice to interactively modify the list you are iterating over?
Yes.
I am a newbie. I also have been confused when I read the tutorial. It recommends make a copy before looping. Then I try.
#--------------------------
Test = [1, 2]
For i in Test:
    Test.append(i)
#--------------------------
But when i execute. The script does not end. I know there must something wrong. So I launch debugger and deserve the list after each loop.
And I see:
Loop 1: [ 1, 2, 1]
Loop 2: [ 1, 2, 1, 2]
Loop 3: [ 1, 2, 1, 2, 1]
Loop 4: [ 1, 2, 1, 2, 1, 2]
......
So you can see that loop will *never* end.
So I think you regard the 'i' as a pointer. After execute one loop the pointer repoints to next element , but at the same time you are appending element. So pointer will *never* repoints to the last element.
How to solve?
Change code to this
#--------------------------
Test = [1, 2]
For i in Test[:] :
    Test.append(i)
#--------------------------