Win8 Strawberry 5.8.9.5 (32)  Thu 11/26/2020  5:05:35
C:\@Work\Perl\monks
>perl
use strict;
use warnings;

my $pattern     = '(.*)\.(.*)\.(.*)';
my $replacement = '$1-$3:$2';
my $flags       = '';

# $got_g is true if /g modifier present in flags.
# ($flags, my $got_g) = sanitize_flags_detect_g($flags);

fixup_forward_slashes($pattern, $replacement);

my $value = 'PR.123.ABC';

print "replacement '$replacement' \n";

my $eval_string = "\$value =~ s/$pattern/$replacement/$flags";
print "eval_string '$eval_string' \n";

eval $eval_string;
print "eval err '$@' \n";
print "output '$value' \n";

sub fixup_forward_slashes { s{/}'\/'g for @_; }
^Z
replacement '$1-$3:$2'
eval_string '$value =~ s/(.*)\.(.*)\.(.*)/$1-$3:$2/'
eval err ''
output 'PR-ABC:123'