Getopt::Std::WithCheck is also a nice way of getting your args, checking they are what they should be, providing defaults, usage warnings etc... all in one go (once you have it set up as you want).

For checking the validity of your args (not sure what they are), there are also a lot of modules for this too

Data::Validate is one i ues a lot

Test::File for checking filenames that are passed etc...

Have a hunt around on CPAN, as this sort of thing is a common problem when creating programs and a lot of solutions are available at little time cost to yourself!