Trollop 1.8.1 released

William Morgan
June 24, 2008 7:07pm

Trollop 1.8.1 is out. This is a minor bugfix release, but 1.8, released a few weeks ago but not really advertised, adds new functionality, so I’m describing that here.

The new functionality is subcommand support, as seen in things like git and svn. This feature is actually trivial to use / implement: you give Trollop a list of stopwords. When it sees one, it stops parsing. The end. That’s all you need.

Here’s how you use it:

  • Call Trollop::options with your global option specs. Pass it the list of subcommands as the stopwords. It will parse ARGV and stop on the subcommand.
  • Parse the next word in ARGV as the subcommand, however you wish. ARGV.shift is the traditional choice.
  • Call Trollop::options again with whatever command-specific options you want.

And that’s it. Simple eh?

It continually amazes me how hard other people make option parsing. I think it’s a holdover from their days of using C or Java. Take a look at synopsis for optparse — it’s a ridiculous amount of work for something simple. Or better yet, look at the synopsis for CmdParse. Having to make a class for each command is a clunky Java-ism. I’m sorry, but it’s true. Subclassing is the one option for specializing code in Java; in Ruby we can be far more sophisticated. Take a look at Ditz’s operator.rb for an example of a subcommand DSL.

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