On 3/31/17, Steven D'Aprano <steve@pearwood.info> wrote:
On Thu, Mar 30, 2017 at 04:23:05PM +0200, Pavol Lisy wrote:
On 3/30/17, Nick Coghlan <ncoghlan@gmail.com> wrote:
On 30 March 2017 at 19:18, Markus Meskanen <markusmeskanen@gmail.com> wrote:
Hi Pythonistas,
yet again today I ended up writing:
d = [[0] * 5 for _ in range(10)]
d = [[0]*5]*10 # what about this?
That doesn't do what you want.
It's actually a common "gotcha", since it makes ten repetitions of the same five element list, not ten *copies*.
Yes. It is clear that I did mistake here (sorry for that!).
Simplified repeating could be probably useful in interactive mode.
I'm sorry, did you just suggest that language features should behave differently in interactive mode than non-interactive mode?
No. I did not suggest it. In contrary: if it is really useful for interactive python (*) then I suggest to implement it generally! (*) - this is matter of discussion where I don't think this proposal will be accepted... Python is multipurpose language which means that something which is not useful in A may be useful in B. Interactive python could be something like discussing with computer where we don't like to talk too much to say a little.
The point of interactive mode is to try out syntax and code and see what it does, before using it in non- interactive scripts. If things behave differently, people will be left confused why the *exact same line of code* works differently in a script and when they try it interactively.
Sorry, this is not true. Not everybody use interactive python only for testing python constructs. (For example see http://ipython.readthedocs.io/en/stable/interactive/shell.html?highlight=she... ) PL