Using ruby's OptionParser to parse sub-commands

Question

I'd like to be able to use ruby's OptionParser to parse sub-commands of the form

COMMAND [GLOBAL FLAGS] [SUB-COMMAND [SUB-COMMAND FLAGS]]

like:

git branch -a
gem list foo

I know I could switch to a different option parser library (like Trollop), but I'm interested in learning how to do this from within OptionParser, since I'd like to learn the library better.

Any tips?

Answer 1

Figured it out. I need to use OptionParser#order!. It will parse all the options from the start of ARGV until it finds a non-option (that isn't an option argument), removing everything it processes from ARGV, and then it will quit.

So I just need to do something like:

global = OptionParser.new do |opts|   # ... end subcommands = {    'foo' => OptionParser.new do |opts|      # ...    end,    # ...    'baz' => OptionParser.new do |opts|      # ...    end  }   global.order!  subcommands[ARGV.shift].order! 

Answer 2

It looks like the OptionParser syntax has changed some. I had to use the following so that the arguments array had all of the options not parsed by the opts object.

begin   opts.order!(arguments) rescue OptionParser::InvalidOption => io   # Prepend the invalid option onto the arguments array   arguments = io.recover(arguments) rescue => e   raise "Argument parsing failed: #{e.to_s()}" end