What's a literal? The only other time I heard about it was studying Shakespare. ;)
I don't know what literal is. So, it won't help me to understand ellipsis, I really thought it was that oval shaped figure. Wiki says: "Literals are often used to initialize variables" https://en.wikipedia.org/wiki/Literal_(computer_programming) I suppose it's just a place holder, though I don't know when I would use it in my every day life. On Thu, Aug 10, 2017 at 8:47 AM, Steven D'Aprano <st...@pearwood.info> wrote: > On Wed, Aug 09, 2017 at 12:06:37PM -0400, C W wrote: > > Dear Python experts, > > > > What exactly does the three dots do? > > > aList = ... > > ... is literal syntax for the Ellipsis singleton object. > > Ellipsis was added to the language at the express request of the numpy > developers. Although numpy is a third-party project outside of the > standard library, it is big enough and important enough that their > requests carry a LOT of weight with the core Python devs. Other features > Python has that were originally added at the request of numpy include: > > - extended slicing with two colons obj[a:b:c] > > - the @ operator used by numpy for matrix multiplication. > > I don't know what Ellipsis is used for by numpy, but now it makes a > convenient pseudo-pass command: > > class X: > ... > > def func(): > ... > > > > It's an ellipsis, a spot holder to later. But what data type is it: > vector, > > matrix? > > Its a singleton object. Think of it as a sibling to None and > NotImplemented, but with optional funny syntactic sugar ... to refer to > it. > > None is a special value used as "no such value", or nil or null; > > NotImplemented is a special value used by operator dunder methods like > __add__ and __mul__ to mean "I can't handle this argument"; > > Ellipsis is a special value used by numpy to mean whatever it is that > numpy uses it to me. > > > -- > Steve > _______________________________________________ > Tutor maillist - Tutor@python.org > To unsubscribe or change subscription options: > https://mail.python.org/mailman/listinfo/tutor > _______________________________________________ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
