> Anyway, I had quite forgotten that you had updated to 2020.05.1 (I thought
> you were
still on 2019.03.1).
I still use the 2019.03 release pretty frequently, but I've got a
newer release around I can check with.
> FYI, I had been trying to write a line of code that calls the ".words"
method on both the input lines
Hm. Something like this?
my $text = q:to/END/;
P123 Green Labels That Say Magenta
P666 Yoda puppets
P912 Corn dogs
END
my @lines = $text.lines;
my @words = $text.words;
say @lines.elems; # 3
say @words.elems; # 12
say @words[5]; # Magenta
On 6/18/20, William Michels <w...@caa.columbia.edu> wrote:
> Hi Joe,
>
> Yup, your test file works perfectly:
>
> Last login: Thu Jun 18 19:38:12 on ttys000
> user@mbook:~$ perl6 regexp_code_interpolation_with_capture_var.t
> ok 1 - case: {} $(... $0 ...)
> ok 2 - case: <{... $0 ... .subst(/\s/, '\s', :g)}>
> ok 3 - case: {} "... $0 ..." (brad gilbert rec)
> ok 4 - case: {} $( ... ) with named capture
> ok 5 - case: {} $( subcall( $0 ) )
> ok 6 - case: {} "&subcall( $0 )"
> user@mbook:~$ perl6 --version
> This is Rakudo version 2020.02.1.0000.1 built on MoarVM version 2020.02.1
> implementing Raku 6.d.
> user@mbook:~$
>
> I'm sure I checked the previous code numerous times, so I'm wondering
> if it's an issue specific to MoarVM version 2020.02.1 ? Anyway, I had
> quite forgotten that you had updated to 2020.05.1 (I thought you were
> still on 2019.03.1).
>
> FYI, I had been trying to write a line of code that calls the ".words"
> method on both the input lines and your product list, but for some
> reason I haven't been able to get to work. Maybe it's time for me to
> update, as well.
>
> Best, Bill.
>
>
>
> On Thu, Jun 18, 2020 at 2:25 PM Joseph Brenner <doom...@gmail.com> wrote:
>>
>> I don't have a 2020.02.1 around, but I see all of this working
>> with both more recent and earlier versions: 2020.05.1 and 2019.03.1.
>>
>> > 1. I got your first "if" line (below) from June 14th to work, the one
>> > you said, "it's not a complete solution":
>> > 1> if $line ~~ / (^P\d+) \s+ <{ %products{$0}.subst(/\s+/, '\s', :g) }>
>> > / {
>>
>> The reason it's "not complete", by the way is that it only covers the
>> case of spaces when in principle the product descriptions might
>> include any regexp meta-character, e.g. "*", "+", "(", ")", etc. Even
>> a hyphen, "-" can mess things up.
>>
>> It's also pretty ugly, and arguably not complete in other ways, it
>> would probably make more sense to drop the "+" in the subst pattern.
>> And really every one of my examples should've pinned the whole
>> expression with a trailing $ to make it an exact match on the
>> description field:
>>
>> if $line ~~ / (^P\d+) \s+ <{ %products{$0}.subst(/\s/, '\s', :g)
>> }> \s* $ / {
>>
>> I'm attaching a test file that exercises this stuff... if you get a
>> chance, could you try to run it? It's supposed to say "ok" six times.
>>
>>
>> On 6/17/20, William Michels <w...@caa.columbia.edu> wrote:
>> > Hi Joe,
>> >
>> > 1. I got your first "if" line (below) from June 14th to work, the one
>> > you said, "it's not a complete solution":
>> > 1> if $line ~~ / (^P\d+) \s+ <{ %products{$0}.subst(/\s+/, '\s', :g) }>
>> > / {
>> >
>> > 2. I got Brad's "if" line (below) from June 15th to work:
>> > 2> if $line ~~ / (^P\d+) \s+ {} "%products{$0}" / {
>> >
>> > 3. However, I couldn't get the {}-updated "if" line (below) you posted
>> > from June 17th to work:
>> > 3> if / (^P\d+) \s+ {} $( %products{$0} ) / {
>> >
>> > 4. Nor could I get your named-capture "if" line (below) from June 17th
>> > to
>> > work:
>> > 4> if / $<prod_id>=(^P\d+) \s+
>> > {}
>> > $( %products{$<prod_id>.Str} ) / {
>> >
>> > By "works", I mean that the third "Corn dogs" example matches, while
>> > the first two fail:
>> >
>> > checking line: P123 Viridian Green Label Saying Magenta
>> > NO: bad line.
>> > checking line: P666 Yoda puppets
>> > NO: bad line.
>> > checking line: P912 Corn dogs
>> > Matched, line looks good
>> >
>> > "This is Rakudo version 2020.02.1.0000.1 built on MoarVM version
>> > 2020.02.1 implementing Raku 6.d."
>> >
>> > HTH, Bill.
>> >
>> >
>> >
>> > On Wed, Jun 17, 2020 at 1:13 PM Joseph Brenner <doom...@gmail.com>
>> > wrote:
>> >>
>> >> Brad Gilbert <b2gi...@gmail.com> wrote:
>> >> > You don't want to use <{…}>, you want to use ""
>> >>
>> >> > if $line ~~ / (^P\d+) \s+ {} "%products{$0}" / {
>> >>
>> >> Well, as contrived examples go this one could be
>> >> improved. Instead of directly dereferencing a
>> >> hash, maybe I should've used a sub call.
>> >>
>> >> > Note that {} is there to update $/ so that $0 works the way you
>> >> > would
>> >> > expect
>> >>
>> >> And notably you really need to know that trick to
>> >> get that to work, but the direction I was
>> >> going using <{ ... }> just works without it.
>> >>
>> >> I can confirm that the gratuitous code block trick fixes
>> >> the approach I really thought should work:
>> >>
>> >> / (^P\d+) \s+ {} $( %products{$0} ) /
>> >>
>> >> This had me wondering if named captures might work
>> >> differently, but they don't, you still need the {}
>> >> there:
>> >>
>> >> / $<prod_id>=(^P\d+) \s+
>> >> {}
>> >> $( %products{$<prod_id>.Str} ) /
>> >>
>> >>
>> >> > Although I would do something like this instead:
>> >> >
>> >> > my ($code,$desc) = $line.split( /\s+/, 2 );
>> >> > if %products{$code} eq $desc {
>> >>
>> >> Yes, there's other simpler ways... I was just
>> >> looking for an excuse to try regex code
>> >> interpolation, particularly when using capture
>> >> variables in the code... and it does turn out
>> >> there's an unexpected (to me) gotcha there.
>> >>
>> >>
>> >> On 6/15/20, Brad Gilbert <b2gi...@gmail.com> wrote:
>> >> > You don't want to use <{…}>, you want to use ""
>> >> >
>> >> > if $line ~~ / (^P\d+) \s+ {} "%products{$0}" / {
>> >> >
>> >> > Note that {} is there to update $/ so that $0 works the way you
>> >> > would
>> >> > expect
>> >> >
>> >> > Although I would do something like this instead:
>> >> >
>> >> > my ($code,$desc) = $line.split( /\s+/, 2 );
>> >> > if %products{$code} eq $desc {
>> >> >
>> >> > On Sun, Jun 14, 2020 at 6:44 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...
>> >> >>
>> >> >
>> >
>
