gistfile1.pl

#!/usr/bin/env perl
use strict;
use warnings;

my $package = get_package( path => $ENV{TM_FILEPATH}, walk_up_to => 'lib' );
my $content = get_content();

if ($content) {
    $content =~ s/^package (.*?);/package $package;/;
    print $content;
}
else {
    print "package $package;\n\nuse strict;\nuse warnings;\n\n1;";
}

sub get_content {
    local $/ = undef;
    return <>;
}

sub get_package {
    my (%args) = @_;
    my @chunks = split qr~/~, $args{path};
    while ( @chunks > 0 ) {
        last if $chunks[0] eq $args{walk_up_to};
        shift @chunks;
    }
    shift @chunks;
    my $pkg = join '::', @chunks;
    $pkg =~ s/\.pm//g;
    return $pkg;
}