package main;
use cacher "/etc";
my $fstab_wc = cacher::wc("fstab");

##</code><code>##

package cacher;
use strict;
use warnings;
use warnings FATAL => qw{ uninitialized }; # larry, this should have been part of warnings.

...

BEGIN {
  my %cachehash;

  my @saved_pkg_args;

  sub import {
    ... pick off the arguments, here /etc/ ...
    ... allow for a default ...
    ... how?? ...
  }

  use File::Glob qw(bsd_glob);

  foreach my $dir (bsd_glob(@saved_pkg_args, !"GLOB_NOCHECK")) {
     foreach my $file (bsd_glob("$dir/*")) {
         $cachehash{"$dir/$file"} = `wc $dir/$file`;
     }
  }

  sub wc { return($cachehash{$_[0]}); }
}