On Mon, Mar 18, 2013 at 7:23 AM, <bartolome.sin...@gmail.com> wrote: > OK. Now I understand it. > > I was confused because when two list are created in two different lines, > Python gives them different ids, but when the two lists are created in the > same line (in a tuple) Python gives them the same id. It doesn't really > matter as these lists are just created and destroyed, as you have said. > > Thank you very much for your fast answer.
Here's something that'll either help you understand another aspect of Python, or totally do your head in. >>> print(id([3])) 14485504 >>> print(id([3])) 14485504 If you print it to stdout, the id can be reused! How is this? Here's what's going on. In interactive mode, the result of the last expression is made available under the name _ (a single underscore): >>> id([3]) 15597160 >>> _ 15597160 Integers are objects, like everything else. (Some of them are pre-made, but big numbers like this aren't - at least, not in this Python. But that's implementation-dependent too.) The retention of this integer object can in some circumstances change where the next object is stored. So you may find that some things behave differently in interactive mode than in a script; or perhaps printing something out instead of letting the interpreter display it will change what happens. You're looking into some extremely unspecified behaviour, here, so anything is allowed to affect it. Which means you might be able to learn all sorts of things about Python's internals! :) ChrisA -- http://mail.python.org/mailman/listinfo/python-list
