use warnings;
use strict;

open my $fh, '<', 'file.txt' or die $!;

my @lines = (
    "this is line 1; foo \n",
    "this is line 2: bar \n",
    "this is line 3: foobar \n",
);

sub create_iter {
    my $arg = shift;
    if (ref $arg eq 'GLOB') {
        return sub {<$arg>};
    }
    elsif (ref $arg eq 'ARRAY') {
        my $index = 0;
        return sub {$arg->[$index++]}
    }
    else { die "Unknown type\n"}
}

print "PRINTING FROM FH\n";
parse_line($fh);
print "\n\nPRINTING FROM ARRAY\n";
parse_line(\@lines);

sub parse_line {
    my $arg = shift;
    my $iter = create_iter($arg);
    while (my $val = $iter->()) {
        print $val if $val =~ /foo/;  
    }
}

##</code><code>##

PRINTING FROM FH
this is line 1; foo
this is line 3: foobar
this is line 4; foobaz

PRINTING FROM ARRAY
this is line 1; foo
this is line 3: foobar