Getting correct behavior is an improvement over my try like so, which
gets the same warning but fails all the lines:
/ (^P\d+) \s+ $(%products{$0}) /
On 6/14/20, yary <not....@gmail.com> wrote:
> I should have read the output!
>
> This one gives the right answers but with lots of warnings
> / (^P\d+) \s+ $("%products{$0}") /
>
> checking line: P123 Viridian Green Label Saying Magenta
>
> Use of Nil in string context
>
> in regex at regex-loop.p6 line 18
>
> Use of Nil in string context
>
> in regex at regex-loop.p6 line 18
>
> Use of uninitialized value %products{''} of type Any in string context.
>
> Methods .^name, .perl, .gist, or .say can be used to stringify it to
> something meaningful.
>
> in regex at regex-loop.p6 line 18
>
> Matched, line looks good
>
> checking line: P666 Yoda puppets
>
> NO: bad line.
> ...
> Why is it reading with an empty-string $0 in %products{''}
>
> -y
>
>
> On Sun, Jun 14, 2020 at 5:47 PM Joseph Brenner <doom...@gmail.com> wrote:
>
>> Well, with the first one it rejects all of my lines, and with the
>> second one it passes all of them.
>>
>> Just to be be clear, my idea is the second line is wrong, and it
>> should flag that one as a problem....
>>
>>
>>
>> On 6/14/20, yary <not....@gmail.com> wrote:
>> > https://docs.raku.org/language/regexes#Regex_interpolation gave me some
>> > ideas
>> >
>> > Try matching against / (^P\d+) \s+ %products{$0} /
>> >
>> > This one also works, in a roundabout way
>> > / (^P\d+) \s+ {"%products{$0}"} /
>> > -y
>> >
>> >
>> > On Sun, Jun 14, 2020 at 4:44 PM Joseph Brenner <doom...@gmail.com>
>> wrote:
>> >
>> >> In part because of the recent discussion here, I decided to
>> >> play around with using Raku code embedded in a regexp.
>> >> I came up with a contrived example where I was going to
>> >> examine a product listing in a text block to see if the product
>> >> descriptions matched the product codes. The valid associations
>> >> I have in a hash, so I'm (1) matching for product codes; (2)
>> >> using embedded code to look-up the associated description in the hash;
>> >> (3) using the returned description inside the regex.
>> >>
>> >> my %products = ( 'P123' => "Green Labels That Say Magenta",
>> >> 'P666' => 'Darkseid For President Bumpersticker',
>> >> 'P912' => "Corn dogs",
>> >> );
>> >>
>> >> my $text = q:to/END/;
>> >> P123 Viridian Green Label Saying Magenta
>> >> P666 Yoda puppets
>> >> P912 Corn dogs
>> >> END
>> >>
>> >> my @lines = $text.lines;
>> >> say @lines;
>> >>
>> >> for @lines -> $line {
>> >> say "checking line: $line";
>> >> ## This line works, but it's not a complete solution:
>> >> if $line ~~ / (^P\d+) \s+ <{ %products{$0}.subst(/\s+/, '\s', :g)
>> >> }>
>> /
>> >> {
>> >> say "Matched, line looks good";
>> >> }
>> >> else {
>> >> say "NO: bad line.";
>> >> }
>> >> }
>> >>
>> >> I'd thought that a line like this would work:
>> >>
>> >> if $line ~~ / (^P\d+) \s+ <{ %products{$0} }> / {
>> >>
>> >> The trouble though is I've got spaces inside the descriptions,
>> >> so if the returned string is treated as a regexp, I get these
>> >> warnings:
>> >>
>> >> Potential difficulties:
>> >> Space is not significant here; please use quotes or :s
>> >> (:sigspace) modifier (or, to suppress this warning, omit the space, or
>> >> otherwise change the spacing)
>> >>
>> >> Reading a bit, I thought this should work
>> >>
>> >> if $line ~~ / (^P\d+) \s+ $( %products{$0} ) / {
>> >>
>> >> That's supposed to use the return string as a literal match.
>> >> Instead I get a lot of strange messages like:
>> >>
>> >> Use of Nil in string context in regex
>> >>
>> >> Flailing around I considered lots of variations like this:
>> >>
>> >> if $line ~~ / (^P\d+) \s+ Q[<{ %products{$0}}>] / {
>> >>
>> >> But I think that ends up treating everything inside the Q[]
>> >> literally, so you never do the hash lookup.
>> >>
>> >> Another thing that might solve this problem is some sort of
>> >> regexp quote function I could use inside the code before
>> >> returning the string, but I don't know what that would be...
>> >>
>> >
>>
>
