NAME

options.rb

DESCRIPTION

options.rb simplifies the common idiom of dealing with keyword options in
ruby functions.  it also deals correctly with symbol vs string keywords and
prevents many subtle programming errors that can arise from doing so
incorrectly.  options.rb doesn't hack ruby's core with one exception: the
method Array#options.

SYNOPSIS

require 'options'

def method(*args, &block)
  args, options = Options.parse(args)

  a = args.shift
  b = args.shift

  force = options.getopt(:force, default = false)
  verbose = options.getopt([:verbose, :VERBOSE])
  foo, bar = options.getopt(:foo, :bar)
end

INSTALL

gem install options

HISTORY

2.2.0:
  - Calculated default values
  - #getopt second arg can be an options hash
2.1.1:
  - Improved samples
  - Improved 1.9 compatibility
2.1.0:
  - 1.9 compatibility
  - Validation of passed options

SAMPLES

<========< samples/a.rb >========>

~ > cat samples/a.rb

  require 'options'

  # options.rb makes it super easy to deal with keyword options in a safe and
  # easy way.
  #

    def method(*args)
      args, options = Options.parse(args)

      force = options.getopt(:force, :default => false)
      p force
    end

    method(:foo, :bar, :force => true)
    method('force' => true)

~ > ruby samples/a.rb

  true
  true

<========< samples/b.rb >========>

~ > cat samples/b.rb

  require 'options'

  # options.rb avoids common mistakes made handling keyword arguments
  #

    def broken(*args)
      options = args.last.is_a?(Hash) ? args.pop : {}
      if options[:force]
        puts 'forcing'
      else
        puts 'broken'
      end
    end

    def nonbroken(*args)
      args, options = Options.parse(args)
      if options.getopt(:force)
        puts 'nonbroken'
      end
    end

    broken('force' => true)
    nonbroken('force' => true)

    def fubar(*args)
      options = args.last.is_a?(Hash) ? args.pop : {}
      verbose = options[:verbose] || true
      if verbose 
        if options[:verbose]
          puts 'verbosely'
        else
          puts 'fubar'
        end
      end
    end

    def nonfubar(*args)
      args, options = Options.parse(args)
      verbose = options.getopt(:verbose)
      if verbose 
        puts 'verbosely'
      else
        puts 'nonfubar'
      end
    end

    fubar(:verbose => false)
    nonfubar(:verbose => false)

~ > ruby samples/b.rb

  broken
  nonbroken
  fubar
  nonfubar

<========< samples/c.rb >========>

~ > cat samples/c.rb

  require 'options'

  # options.rb hacks ruby core in exactly one way - the method Array#options
  #

    def method(*args)
      options = args.options
      p :args => args
      p :options => options
    end

    method(:a, :b, :k => :v)

    def method2(*args)
      options = args.options.pop
      p :args => args
      p :options => options
    end

    method2(:a, :b, :k => :v)

~ > ruby samples/c.rb

  {:args=>[:a, :b, {:k=>:v}]}
  {:options=>{:k=>:v}}
  {:args=>[:a, :b]}
  {:options=>{:k=>:v}}

<========< samples/d.rb >========>

~ > cat samples/d.rb

  require 'options'

  # options.rb makes it easy to provide good error messages when people
  # misuse a method.
  #

    def method(*args)
      args, options = Options.parse(args)
      options.validate(:force)

      force = options.getopt(:force, default=false)
      p force
    end

    method(:foo, :bar, :misspelled_option => true)

~ > ruby samples/d.rb

  /Users/pezra/Development/options/lib/options.rb:188:in `validate': Unrecognized options: misspelled_option (ArgumentError)
  	from samples/d.rb:9:in `method'
  	from samples/d.rb:15:in `<main>'

<========< samples/e.rb >========>

~ > cat samples/e.rb

  require 'options'
  require 'date'

  # You can also provide a lambda (or anything that responds to `#call`)
  # as the default value.  If default responds to `#call` the return
  # value of `#call` be used as the default value.  Default value
  # calculation procs will not be called when the option is
  # present. This allows for runtime calculation of default values, or
  # for defaults that are expensive to create.

    def method(*args)
      args, options = Options.parse(args)

      force = options.getopt(:force, :default => lambda{Date.today.day.even?})
      p force
    end

    method(:foo)  # force will be true on even days and false on odd days

~ > ruby samples/e.rb

  true