optarg

Yet another Crystal library for parsing command-line options and arguments.

optarg is good enough for parsing options. However there's no feature for formatting help, subcommands... etc. If you prefer a more feature-rich library, try cli.

Installation

Add this to your application's shard.yml:

dependencies:
  optarg:
    github: mosop/optarg

Features

Accessor

class Model < Optarg::Model
  string "--foo"
end

result = Model.parse(%w(--foo bar))
result.foo # => "bar"

Nilable Accessor

class Model < Optarg::Model
  string "--foo"
end

result = Model.parse(%w())
result.foo? # => nil
result.foo # raises KeyError

Synonyms

class Model < Optarg::Model
  string %w(-f --file)
end

result = Model.parse(%w(-f foo.cr))
result.f # => "foo.cr"
result.file # => "foo.cr"

Boolean

class Model < Optarg::Model
  bool "-b"
end

result = Model.parse(%w(-b))
result.b? # => true

Array

class Model < Optarg::Model
  array "-e"
end

result = Model.parse(%w(-e foo -e bar -e baz))
result.e # => ["foo", "bar", "baz"]

Concatenation

class Model < Optarg::Model
  bool "-a"
  bool "-b"
end

result = Model.parse(%w(-ab))
result.a? # => true
result.b? # => true

Default Value

class Model < Optarg::Model
  string "-s", default: "string"
  bool "-b", default: false
  array "-a", default: %w(1 2 3)
end

result = Model.parse(%w())
result.s  # => "string"
result.b? # => false
result.a  # => ["1", "2", "3"]

Negation

class Model < Optarg::Model
  bool "-b", default: true, not: "-B"
end

result = Model.parse(%w(-B))
result.b? # => false

Arguments

class Model < Optarg::Model
  string "-s"
  bool "-b"
end

result = Model.parse(%w(foo -s string bar -b baz))
result.args # => ["foo", "bar", "baz"]

Named Argument

class Model < Optarg::Model
  arg "src_dir"
  arg "build_dir"
end

result = Model.parse(%w(/path/to/src /path/to/build and more))
result.args.src_dir # => "/path/to/src"
result.args.build_dir # => "/path/to/build"
result.args # => ["/path/to/src", "/path/to/build", "and", "more"]
result.args.named # => {"src_dir" => "/path/to/src", "build_dir" => "/path/to/build"}
result.args.nameless # => ["and", "more"]

Inheritance (Reusable Model)

class Animal < Optarg::Model
  bool "--sleep"
end

class Cat < Animal
  bool "--mew"
end

class Dog < Animal
  bool "--woof"
end

Cat.parse(%w()).responds_to?(:sleep?) # => true
Dog.parse(%w()).responds_to?(:sleep?) # => true

Handler

class Model < Optarg::Model
  on("--goodbye") { goodbye! }

  def goodbye!
    raise "Goodbye, world!"
  end
end

Model.parse %w(--goodbye) # raises "Goodbye, world!"

Required Arguments and Options

class Profile < Optarg::Model
  string "--birthday", required: true
end

Profile.parse %w() # raises a RequiredArgumentError exception.

class Compile < Optarg::Model
  arg "source_file", required: true
end

Compile.parse %w() # raises a RequiredOptionError exception.

Minimum Length of Array

class Multiply < Optarg::Model
  array "-n", min: 2

  def run
    puts options.n.reduce{|n1, n2| n1 * n2}
  end
end

Multiply.parse %w(-n 794) # raises a MinimumLengthError exception.

Custom Initializer

class The
  def message
    "Someday again!"
  end
end

class Model < Optarg::Model
  def initialize(argv, @the : The)
    super argv
  end

  on("--goodbye") { raise @the.message }
end

Model.new(%w(--goodbye), The.new).parse # raises "Someday again!"

Stop and Termination

class Model < Optarg::Model
  bool "-b", stop: true
end

result = Model.parse(%w(foo -b bar))
result.b? # => true
result.args # => ["foo"]
result.unparsed_args # => ["bar"]

class Model < Optarg::Model
  terminator "--"
end

result = Model.parse(%w(foo -- bar))
result.args # => ["foo"]
result.unparsed_args # => ["bar"]

Usage

require "optarg"

and see Features.

Release Notes

• v0.3.0
  • Stop and Termination
  • (Breaking Change) "--" (double dash) is no longer a special argument by default. Use the Model.terminator method.
• v0.2.0
  • (Breaking Change) Model#args separates arguments into named and nameless. #args itself returns both named and nameless arguments.
• v0.1.14
  • Required Arguments and Options
  • Minimum Length of Array
• v0.1.13
  • Accessible Argument
• v0.1.12
  • Array
• v0.1.9
  • Concatenation
• v0.1.3
  • Custom Initializer
• v0.1.2
  • Synonyms
• v0.1.1
  • Handler

Development

[WIP]

Contributing

1. Fork it ( https://github.com/mosop/optarg/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request

Contributors

• mosop - creator, maintainer