On Wednesday, November 18, 2015 at 5:12:44 PM UTC-5, Ian wrote: > On Wed, Nov 18, 2015 at 2:08 PM, fl <com> wrote: > > Hi, > > > > I have tried the below function and find that it can remember the previous > > setting value to 'val'. I think the second parameter has something on this > > effect, but I don't know the name and function of '=[]' in this application. > > > > Could you explain a little to me? > > Thanks, > > > > > > def eList(val, list0=[]): > > list0.append(val) > > return list0 > > list1 = eList(12) > > list1 = eList('a') > > The list0 parameter has a default value, which is [], an initially > empty list. The default value is evaluated when the function is > defined, not when it is called, so the same list object is used each > time and changes to the list are consequently retained between calls.
Thanks. The amazing thing to me is that the following two line codes: list1 = eList(12) list2 = eList('a') will have both list1 and list2 the same cascaded values: list1 Out[2]: [12, 'a'] list2 Out[3]: [12, 'a'] I have known object concept in Python. 1. Why do they have the same list value? Function eList must be for this purpose? 2. If I want to have two separate lists, how to avoid the above result? Function eList is not for this purpose? Thanks again. -- https://mail.python.org/mailman/listinfo/python-list