I got the point for //.
Another question is about calling the method sort with a code block. I can
understand
@x .= sort({ ... });
But I don't quite understand why this form also works.
@x .= sort: { ... };
I look into the documentation for infix ":", https://docs.perl6.org/routine/:
<https://docs.perl6.org/routine/:> , and it explains something like this:
Used as an argument separator just like infix , and marks the argument to its
left as the invocant. That turns what would otherwise be a function call into a
method call.
substr('abc': 1); # same as 'abc'.substr(1)
Infix : is only allowed after the first argument of a non-method call. In other
positions, it's a syntax error.
How does the above explanation related to the case in hand @x .= sort: { ... };
? Is sort an invocant? Or I miss something.
Regards
Xin
> On Jun 9, 2018, at 12:44 PM, Brandon Allbery <[email protected]> wrote:
>
> More precisely, at that point you have a bunch of numbers, but possibly not
> as many as expected if some of the components weren't numeric (or all of
> them, as when there are files present that aren't the expected logs). Which
> means some or all of those variables will be undefined instead of numbers.
> The // replaces those with the following value (0), so they do something
> sensible when sorted instead of producing warnings.
>
> On Sat, Jun 9, 2018 at 11:40 AM Xin Cheng <[email protected]
> <mailto:[email protected]>> wrote:
> This is very interesting. But I wonder how it works. I can understand the
> first line
>
> my ($month, $day, $year, $hour, $minute, $second) = .comb(/\d+/);
>
> Which extract the variables from $_. What is the second line doing, it is
> very concise.
>
> ($year // 0, $month // 0, $day // 0, $hour // 0, $minute // 0,
> $second // 0, $_);
>
> Could somebody explain in some more words.? What does // do? Why it sorts
> the array?
>
> Regards
>
> Xin
>
>> On Jun 9, 2018, at 12:51 AM, Timo Paulssen <[email protected]
>> <mailto:[email protected]>> wrote:
>>
>> That's unnecessarily long and complicated, here's how you can do it much
>> easier:
>>
>> @x.sort: {
>> my ($month, $day, $year, $hour, $minute, $second) = .comb(/\d+/);
>> ($year // 0, $month // 0, $day // 0, $hour // 0, $minute // 0,
>> $second // 0, $_);
>> }
>>
>> Trying it on some input data:
>>
>> cimtrak.log.06-08-2018_16:07:39.zip
>> cimtrak.log.06-08-2018_17:07:39.zip
>> cimtrak.log.07-08-2018_06:07:39.zip
>> cimtrak.log.07-08-2018_16:07:39.zip
>> cimtrak.log.12-08-2016_06:07:39.zip
>> cookies
>> asbestos
>> fire engine
>> perl6
>> butterflies
>>
>> results in:
>>
>> asbestos
>> butterflies
>> cookies
>> fire engine
>> perl6
>> cimtrak.log.12-08-2016_06:07:39.zip
>> cimtrak.log.06-08-2018_16:07:39.zip
>> cimtrak.log.06-08-2018_17:07:39.zip
>> cimtrak.log.07-08-2018_06:07:39.zip
>> cimtrak.log.07-08-2018_16:07:39.zip
>>
>> This is the schwartzian transform that was mentioned in another mail.
>> why it wasn't actually shown, i have no clue :)
>>
>> Hope that helps
>> - Timo
>
>
>
> --
> brandon s allbery kf8nh sine nomine associates
> [email protected] <mailto:[email protected]>
> [email protected] <mailto:[email protected]>
> unix, openafs, kerberos, infrastructure, xmonad http://sinenomine.net
> <http://sinenomine.net/>
