foca / clap

Command line argument parsing

Clap

Command line argument parsing for simple applications.

Description

Clap is a small library that can be bundled with your command line application. It covers the simple case of executing code based on the flags or parameters passed.

Usage

Using Clap is simple: just pass ARGV and a hash of flags, and it will extract the arguments as needed.

Clap.run ARGV,
  "-a" => lambda { |param| ... },
  "-b" => lambda { ... }

To better illustrate the usage, in the following examples ARGV is replaced by an array of strings.

If you want your command line application to require a file or display a version number, you can configure it like this:

Clap.run %w(-r foo -v),
  "-r" => lambda { |file| require file },
  "-v" => lambda { puts VERSION }

This will detect the -r or -v flags and act accordingly. Note that it will also read the necessary number of parameters for each flag based on the arity of the passed lambda.

Another example, for an application that takes a -v flag and also a list of files:

files = Clap.run %w(-v foo bar),
  "-v" => lambda { puts VERSION }

files == %w(foo bar)

If you want to allow flag aliases, pass an array as the key of the hash of flags:

Clap.run %w(--version),
  ["-v", "--version"] => lambda { puts VERSION }

Using methods instead of lambdas

If you prefer to group the options in a module or class, you can still attach the methods to command line flags:

class MyApp
  module CLI
    def self.version
      puts VERSION
    end

    def self.help(command)
      puts HELP[command]
    end
  end
end

Clap.run %w(-v -h foo),
  "-v" => MyApp::CLI.method(:version),
  "-h" => MyApp::CLI.method(:help)

When in doubt, check the tests for the different use cases.

Installation

$ gem install clap

License

Copyright (c) 2010 Michel Martens

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.