Medium Example

A more complex example

opts = Trollop::options do
  version "cool-script v0.1 (code-name: bananas foster)"
  banner "This script is pretty cool."
  opt :juice, "use juice"
  opt :milk, "use milk"
  opt :litres, "quantity of liquid", :default => 2.0
  opt :brand, "brand name of the liquid", :type => :string
  opt :config, "config file path", :type => String, :required => true
  opt :drinkers, "number of people drinking the liquid", :default => 6
end
Trollop::die :drinkers, "must be value a greater than zero" if opts[:drinkers] < 1
Trollop::die :config, "must point to an existing file" unless File.exist?(opts[:config]) if opts[:config]

Custom Banner and Version

The banner directive replaces the default banner with a custom banner.
The version directive auto-creates a :version long-option and provides a version message.

$ ./medium_example.rb -h
This script is pretty cool.
  -j, --juice           use juice
  -m, --milk            use milk
  -l, --litres=<f>      quantity of liquid (default: 2.0)
  -b, --brand=<s>       brand name of the liquid
  -c, --config=<s>      config file path
  -d, --drinkers=<i>    number of people drinking the liquid (default: 6)
  -v, --version         Print version and exit
  -h, --help            Show this message

$ ./medium_example.rb -v
cool-script v0.1 (code-name: bananas foster)

Trollop type-checking

Types are given for some options. Other types are implied from the given default. Also see Option Types.

Required command-line options

Setting :required => true on the opt will require a user to set that that option on the command-line. This applies to any set of command-line options except when help or version are requested

./medium_example.rb  ## no options given
Error: option --config must be specified.

Trollop Errors

Trollop::die can be used to form fatal error messages when conditions are not met.

$ ./medium_example.rb -d 1 -c foo.txt
Error: argument --config must point to an existing file.
$ ./medium_example.rb -d 0 -c foo.txt
Error: argument --drinkers must be value greater than zero.

Dependencies and conflicts

A limited amount of dependency and conflict resolution can be used in Trollop::options

opts = Trollop::options do
  version "cool-script v0.2 (code-name: key-lime-pie)"
  banner "This script is pretty cool."
  opt :juice, "use juice"
  opt :fruit, "fruit used to make the juice", :type => :string
  opt :milk, "use milk"
  opt :beer, "use beer"
  conflicts :milk, :juice, :beer
  depends :fruit, :juice
end

conflicts requires :milk, :juice and :beer to be mutually exclusive options. depends requires :juice and :fruit to be given if either of them are given.

$ ./medium_example_2.rb --juice --milk 
Error: --milk conflicts with --juice.

$ ./medium_example_2.rb --juice --milk --beer
Error: --milk conflicts with --juice.

$ ./medium_example_2.rb --juice --beer
Error: --juice conflicts with --beer.

$ ./medium_example_2.rb --fruit
Error: --fruit requires --juice.

$ ./medium_example_2.rb --juice 
Error: --juice requires --fruit.