#!/usr/bin/perl

my $test = 'abc , def';

for my $sub qw/trim_start trim_end trim_start trim_end/ {
    $test =~ /([\s\w]+),([\s\w]+)/;

    $sub->($1, $2);
}

sub trim_start {
    while (@_) {
        my $string = shift @_;
        $string =~ s/\A\s+//ms;

        print "$string\n";
    }
}

sub trim_end {
    while (@_) {
        my $string = shift @_;
        $string =~ s/\s+\z//ms;

        print "$string\n";
    }
}