gistfile1.pl

#!/usr/bin/env perl

use 5.012;
use warnings;
use autodie;

# quick & crude example for comment in:
# http://stackoverflow.com/questions/3308149/perl-function-knowing-receiver-type/3308591#3308591

{
    package MyFile;
    
    sub read {
        my ($class, $filename) = @_;
        bless {
            filename => $filename,
            fh       => do { open my $fh, '<', $filename; $fh },
        }, $class;
    }
    
    sub as_list {
        my $self = shift;
        return (readline $self->{fh});
    }
    
    sub as_hash {
        my $self = shift;
        # arbitary hash info follows
        my $count;
        return map { chomp; ++$count => $_ } readline $self->{fh};
    }
}


my @x = MyFile->read('some_file.txt')->as_lines;

my %y = MyFile->read('another_file.txt')->as_hash;