Slop

Slop is a simple option parser with an easy to remember syntax and friendly API.

Installation

Rubygems

gem install slop

GitHub

git clone git://github.com/injekt/slop.git
gem build slop.gemspec
gem install slop-<version>.gem

Usage

# parse assumes ARGV, otherwise you can pass it your own Array
opts = Slop.parse do
  on :v, :verbose, 'Enable verbose mode'           # boolean value
  on :n, :name, 'Your name', true                  # option requires a compulsory argument
  on :s, :sex, 'Your sex', :optional => false      # the same thing
  on '-a', '--age', 'Your age', :optional => true  # optional argument
end

# if ARGV is `-v --name 'lee jarvis' -s male`
opts.verbose? #=> true
opts.name?    #=> true
opts[:name]   #=> 'lee jarvis'
opts.age?     #=> false
opts[:age]    #=> nil

For more information about creating options, see the Creating Options wiki page.

You can also return your options as a Hash

opts.to_hash #=> {'name' => 'Lee Jarvis', 'verbose' => true, 'age' => nil, 'sex' => 'male'}

If you want some pretty output for the user to see your options, you can just send the Slop object to puts or use the help method.

puts opts
puts opts.help

Will output something like

-v, --verbose      Enable verbose mode
-n, --name         Your name
-a, --age          Your age

You can also add a banner using the banner method

opts = Slop.parse do
  banner "Usage: foo.rb [options]"
end

Helpful Help

Long form:

Slop.parse do
  ...
  on :h, :help, 'Print this help message', :tail => true do
    puts help
    exit
  end
end

Shortcut:

Slop.parse :help => true do
  ...
end

Parsing

Slop's pretty good at parsing, let's take a look at what it'll extract for you

Slop.parse do
  on 's', 'server', true
  on 'p', 'port', true, :as => :integer
  on 'username', true, :matches => /[^a-zA-Z]+$/
  on 'password', true
end

Now throw some options at it:

-s ftp://foobar.com -p1234 --username=FooBar --password 'hello there'

Here's what we'll get back

{
    :server=>"ftp://foobar.com",
    :port=>1234,
    :username=>"FooBar",
    :password=>"hello there"
}

Events

If you'd like to trigger an event when an option is used, you can pass a block to your option. Here's how:

Slop.parse do
  on :V, :version, 'Print the version' do
    puts 'Version 1.0.0'
    exit
  end
end

Now when using the --version option on the command line, the trigger will be called and its contents executed.

Yielding Non Options

If you pass a block to Slop#parse, Slop will yield non-options as they're found, just like OptionParser does it.

opts = Slop.new do
  on :n, :name, :optional => false
end

opts.parse do |arg|
  puts arg
end

# if ARGV is `foo --name Lee bar`
foo
bar

Negative Options

Slop also allows you to prefix --no- to an option which will force the option to return a false value.

opts = Slop.parse do
  on :v, :verbose, :default => true
end

# with no command line options
opts[:verbose] #=> true

# with `--no-verbose`
opts[:verbose] #=> false
opts.verbose?  #=> false

Short Switches

Want to enable multiple switches at once like rsync does? By default Slop will parse -abcd as the option a with the argument bcd, this can be disabled by passing the :multiple_switches option to a new Slop object.

opts = Slop.new(:strict, :multiple_switches) do
  on :a, 'First switch'
  on :b, 'Second switch'
  on :c, 'Third switch'
end

opts.parse

# Using `-ac`
opts[:a] #=> true
opts[:b] #=> false
opts[:c] #=> true

Lists

You can of course also parse lists into options. Here's how:

opts = Slop.parse do
  opt :people, true, :as => Array
end

# ARGV is `--people lee,john,bill`
opts[:people] #=> ['lee', 'john', 'bill']

Slop supports a few styles of list parsing. Check out this wiki page for more info.

Strict Mode

Passing strict => true to Slop.parse causes it to raise a Slop::InvalidOptionError when an invalid option is found (false by default):

Slop.new(:strict => true).parse(%w/--foo/)
# => Slop::InvalidOptionError: Unknown option -- 'foo'

Features

Check out the following wiki pages for more features:

• Ranges
• Auto Create
• Commands

Woah woah, why you hating on OptionParser?

I'm not, honestly! I love OptionParser. I really do, it's a fantastic library. So why did I build Slop? Well, I find myself using OptionParser to simply gather a bunch of key/value options, usually you would do something like this:

require 'optparse'

things = {}

opt = OptionParser.new do |opt|
  opt.on('-n', '--name NAME', 'Your name') do |name|
    things[:name] = name
  end

  opt.on('-a', '--age AGE', 'Your age') do |age|
    things[:age] = age.to_i
  end

  # you get the point
end

opt.parse
things #=> { :name => 'lee', :age => 105 }

Which is all great and stuff, but it can lead to some repetition. The same thing in Slop:

require 'slop'

opts = Slop.parse do
  on :n, :name, 'Your name', true
  on :a, :age, 'Your age', true, :as => :int
end

opts.to_hash(true) #=> { :name => 'lee', :age => 105 }