> On 1 May 2018, at 22:02, Sean McAfee <eef...@gmail.com> wrote: > > Today I wanted to write an infinite sequence of Dates starting from today, > but I accidentally wrote two dots instead of three as I'd intended. I was > surprised to find that it seems to work as one might expect, eg: > > (Date.today .. *)[7] # one week from today > > The online docs say that Ranges are only for numbers and strings, so how is > it that this works? Is it an accident, or can anything that has a "succ" > method be in a Range, or...?
Indeed, when a Range consists of something else than we normally expect from a range (like a number), the iterator falls back on calling the .succ method on the object to get the succeeding object until it smart-matches with the end condition. Since the Date class provides that method, this just works. By the way, this same logic is used for ++ and — (the latter calling the .pred method): $ 6 'my $date = Date.today; say $date++ for ^5' 2018-05-02 2018-05-03 2018-05-04 2018-05-05 2018-05-06 $ 6 'my $date = Date.today; say $date-- for ^5' 2018-05-02 2018-05-01 2018-04-30 2018-04-29 2018-04-28 Takeaway from this: if you have an object that you want to be incrementable and usable in Ranges, simply provide .succ and .pred methods. Getting back to maybe your original question: if you want the date 7 days from now, you can just use integer arithmetic: $ 6 'say Date.today + 7' 2018-05-09
