dreck

A stupid parser for trailing arguments.

There are lots of good argument parsers for Ruby: OptionParser, Slop, trollop, cocaine, etc.

Most of these are great for parsing and typechecking options, but none provide a good interface to the arguments that often trail the options.

Dreck does exactly that. Give it a specification of arguments (and their types) to expect, and it will give you a nicely typechecked result.

$ gem install dreck

Dreck is best used in conjunction with an option parser like Slop, which can provide an array of arguments with options already filtered out:

opts = Slop.parse do |s|
  # ...
end

opts.args # => [ "/dev/urandom", "/dev/sda", "512" ]

results = Dreck.parse opts.args, strict: true do
  file   :input
  symbol :output
  int    :blocksize
end

results[:input] # => "/dev/urandom"
results[:output] # => :"/dev/sda"
results[:blocksize] # => 512

Lists are also supported:

result = Dreck.parse opts.args do
  string :uuid
  list   :file, :inputs, count: 2
  list   :int, :nums
end

result[:uuid] # => "01aa84ab-5b2c-4861-adc9-fcc6990a5ca5"
result[:inputs] # => ["/tmp/foo", "/tmp/bar"]
result[:nums] # => [1, 2, 3, 4, 5]

• Guarding against multiple unbound lists/unbound list before scalar types
• Custom types?