Perl6 search then replace with output of subroutine
Ok so we'll start by making a function that just returns our input repeated 5 times
sub func($a) { $a x 5 };
Make our string
my $s = "Here is a needle";
And here's the replace
$s ~~ s/"needle"/{func($/)}/;
Couple of things to notice. As we just want to match a string we quote it. And our output is effectively a double quoted string so to run a function in it we use {}
. No need for the e
modifier as all strings allow for that kind of escaping.
The docs on substitution mention that the Match object is put in $/
so we pass that to our function. In this case the Match object when cast to a String just returns the matched string. And we get as our final result.
Here is a needleneedleneedleneedleneedle
There is no e
modifier in Perl 6; instead, the right hand part is treated like a double-quoted string. The most direct way to call a function is therefore to stick an &
before the function name and use function call interpolation:
# An example function
sub func($value) {
$value.uc
}
# Substitute calling it.
my $str = "I sew with a needle.";
$str ~~ s/(needle)/&func($0)/;
say $str;
Which results in "I sew with a NEEDLE.". Note also that captures are numbered from 0 in Perl 6, not 1. If you just want the whole captured string, pass $/
instead.