In P5, I am able to do something like this
my ($var1, $var2, $var3) = $string =~ /(.+)\s(.+)\s(.+)/;
How do I do the same in Perl 6? If I do the same syntax, the $var1 will hold the entire $string value.
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2 Answers
The result from that match is a Match object, which by itself won't behave like a list, and therefore won't expand into the three variables. However, the Match object has a "list" method that does what you want. Here's an example:
my $string = "hello how are you";
my ($var1, $var2, $var3) =
($string ~~ /(.+)\s(.+)\s(.+)/).list;
say "$var1 and $var2 and $var3
# Output: hello how and are and you
A few further things to point out:
- Since .+ is a greedy match, and it also accepts spaces, the first capture will eat up two words.
- Surely the code in the question is a simplified example, but if you ever need to split text into words, maybe the
wordsmethod does what you want. Of course, you'll want to check what exactly you want: Split by spaces? Only return alphabetic characters, so that periods and commas aren't in the final result? etc. - If you do need to match the same thing multiple times, maybe the
combmethod is actually more helpful?
2 Comments
Zarul Zakuan
ive been using P6 for like less than a week now and I got a sense that this is not Perl at all :-)
Scimon Proctor
It is like Perl5 in a lot of way but yes if you expect it to work exactly the same way you'll maybe trip up a few times. I can recommend looking at docs.perl6.org/language/5to6-nutshell the Perl5 to Perl6 guide for pointers :)
my $string = 'foo bar baz';
my $match = $string ~~ /(.+)\s(.+)\s(.+)/;
say $match; # 'foo bar baz'
say $match[0]; # 'foo'
say $match[1]; # 'bar'
say $match[2]; # 'baz'
my ($foo, $bar, $baz) = @$match;
say $foo; # 'foo'
say $bar; # 'bar'
say $baz; # 'baz'
therefore
my ($foo, $bar, $baz) = @($string ~~ /(.+)\s(.+)\s(.+)/);
3 Comments
Zarul Zakuan
Thanks Tomalak. On a different note, why $match[0] if its an array? I thought in P6 the sigil now changed to @ ?
timotimo
That's right, but in perl 6 there are no longer references, so you don't have to dereference the list object in order to access its individual elements via subscript.
Zarul Zakuan
i like this method instead of .list. this is more Perl-ish :-) Thanks!