PathExpander helps pre-process command-line arguments expanding directories into their constituent files. It further helps by providing additional mechanisms to make specifying subsets easier with path subtraction and allowing for command-line arguments to be saved in a file. NOTE: this is NOT an options processor. It is a path processor (basically everything else besides options). It does provide a mechanism for pre-filtering cmdline options, but not with the intent of actually processing them in PathExpander. Use OptionParser to deal with options either before or after passing ARGV through PathExpander.