Pass regex into perl subroutine - regex

Question

The Situation
I am in the process of creating a simple template file that will aid in creating future scripts for doing various tasks via command line on *nix systems. As part of this, I might like to ask the user to input data which needs to validated against a regular expression that is supplied in the source code.
The Issue
Errors are begin generated when I attempt to run the Perl code via command line. I am attempting to pass a regular expression into the repeat subroutine and I'm not sure how to exactly do this. I am aware that I can execute a string using eval, however this is something that I would like to avoid due to convention.
The errors:
Use of uninitialized value $_ in pattern match (m//) at scripts/template line 40.
Use of uninitialized value $resp in concatenation (.) or string at scripts/template line 37.
The code:
#!/usr/bin/env perl
use strict;
use warnings;
use Cwd;
use Term::ANSIColor;
use Data::Dumper;
my $log = "template.log";
my $task = "template";
my $cwd = getcwd();
my $logPath = $cwd . "/". $log;
print ucfirst($task) . " utility starting...\n";
system("cd ~/Desktop");
system("touch " . $log);
&writeLog("Test");
sub writeLog {
open(my $fh, '>>', $logPath) or die "Could not open file '$log' $!";
print $fh $_[0] . localtime() . "\n";
close $fh;
return 1;
}
sub ask {
my $question = $_[0];
my $input = $_[1];
my $resp = <>;
chomp($resp);
}
sub repeat {
my $pat = $_[0];
my $resp = $_[1];
print $pat . "\n";
print $resp . "\n";
}
&repeat(/foo|bar/i, "y");
What I have tried:
Based on these sources:
Match regex and assign results in single line of code
How to assign result of a regex match to a new variable, in a single line?
sub repeat {
my $pat =~ $_[0];
my $resp = $_[1];
if($pat !~ $resp) {
print "foo\n";
} else {
print "bar\n";
}
}
Any help is appreciated!

Answer 1

To create a regular expression for use later, we use qr//:
my $regexp = qr/^Perl$/;
This compiles the regular expression for use later. If there's a problem with your regular expression, you'll hear about it immediately. To use this pre-compiled regular expression you can use any of the following:
# See if we have a match
$string =~ $regexp;
# A simple substitution
$string =~ s/$regexp/Camel/;
# Comparing against $_
/$regexp/;

Answer 2

A bare regex literal like /.../ matches agains $_. To create an independent regex object, use qr// quotes:
repeat(qr/foo|bar/i, "y");
(and please don't invoke subs like &sub unless you know when and why this is neccessary.)