Ralph, the last value in all functions are not sunk by default, so of
course the last one in `TWEAK` is not sunk by default.
This is intended behaviour.
It is up to the code that calls a function to sink the result if that is
the desired behaviour.
sub foo {
'a b c'.words».uc.map: *.say;
}
my $ = foo(); # nothing is printed
sink foo(); # «ABC» is printed
The bug is that the calling code is not sinking the result.
On Sat, Mar 13, 2021 at 8:05 PM Ralph Mellor <ralphdjmel...@gmail.com>
wrote:
> Here's a golf:
>
> class { submethod TWEAK { Any.map: {say 99} } }.new; #
> class { submethod TWEAK { Any.map: {say 99}; 42 } }.new; # 99
> class { submethod TWEAK (--> 42) { Any.map: {say 99} } }.new; # 99
>
> The last line in a `BUILD` or `TWEAK` submethod is not eagerly evaluated
> by default.
>
> That sounds like a bug to me. But if not, and in the meantime,
> because your `$!filelist.lines...` line is the last one in your `TWEAK`
> submethod, the `@!show` array is being left empty, so the value to
> the right of `%` evaluates to zero, hence the error message you're seeing.
>
> On Sat, Mar 13, 2021 at 8:30 PM <mimosin...@gmail.com> wrote:
> >
> > Hi,
> >
> > When working with this week challenge for the PerlWeeklyChallenge, I
> noticed this behaviour with TWEAK:
> >
> > This does not work:
> > submethod TWEAK {
> > $!filelist.lines».split(',').map( -> ($a, $b) { @!show.push: ( $a,
> $b ) });
> > }
> >
> > This works:
> > submethod TWEAK {
> > $!filelist.lines».split(',').map( -> ($a, $b) { @!show.push: ( $a,
> $b ) });
> > return;
> > }
> >
> > It also works with other commands instead of 'return' (like assigning a
> value to a variable). From the examples in the documentation, I am not
> certain this is the expected behaviour.
> >
> > Thanks for this extraordinary language,
> >
> > Joan
> >
> >
> > P.S: This is the context where the command appears. Apologies for the
> messy-Raku,
> > ------------------------------
> > use Test;
> >
> > my $data = '1709363,"Les Miserables Episode 1: The Bishop (broadcast
> date: 1937-07-23)"
> > 1723781,"Les Miserables Episode 2: Javert (broadcast date: 1937-07-30)"
> > 1723781,"Les Miserables Episode 3: The Trial (broadcast date:
> 1937-08-06)"
> > 1678356,"Les Miserables Episode 4: Cosette (broadcast date: 1937-08-13)"
> > 1646043,"Les Miserables Episode 5: The Grave (broadcast date:
> 1937-08-20)"
> > 1714640,"Les Miserables Episode 6: The Barricade (broadcast date:
> 1937-08-27)"
> > 1714640,"Les Miserables Episode 7: Conclusion (broadcast date:
> 1937-09-03)"';
> >
> > class Movies {
> >
> > has $.starttime;
> > has $.currenttime;
> > has $.filelist;
> > has @!show; # ( [ time, show ] )
> >
> > submethod TWEAK {
> > # miliseconds -> seconds
> > $!filelist.lines».split(',').map( -> ($a, $b) { @!show.push: ( $a,
> $b ) });
> > return;
> > }
> >
> > method what-show() {
> > my $position = ( $!currenttime - $!starttime ) %
> @!show[*;0].sum/1000;
> > my ($time, $show);
> > for @!show[*;0] -> $show-time {
> > $time += $show-time;
> > return @!show[$show++;1] if $time > $position;
> > }
> > }
> > }
> >
> > my $mv = Movies.new(
> > starttime => '1606134123',
> > currenttime => '1614591276',
> > filelist => $data
> > );
> >
> > is $mv.what-show, '"Les Miserables Episode 1: The Bishop (broadcast
> date: 1937-07-23)"';
>
