I need to parse a command line like
script.rb <mandatory filename> [options]
['--mandatory-filename'] + ARGV
parse! with optparse, then scan the ARGV and raise if ARGV is empty. Like so:
op.parse! filename = ARGV.pop raise "Need to specify a file to process" unless filename
The mandatory filename will not be processed by the
OptionParser and will be left for you in ARGV - if it's not there, just raise manually.