Usage Example

Usage Example

CLIs can be built by using a Executable as a mixin, or by subclassing Executable::Command. Methods seemlessly handle command-line options. Writer methods (those ending in '=') correspond to options and query methods (those ending in '?') modify them to be boolean switches.

For example, here is a simple "Hello, World!" commandline tool.

    require 'executable'

    class HelloCommand
      include Executable

      # Say it in uppercase?
      def loud=(bool)
        @loud = bool
      end

      #
      def loud?
        @loud
      end

      # Show this message.
      def help!
        cli.show_help
        exit
      end
      alias :h! :help1

      # Say hello.
      def call(name)
        name = name || 'World'
        str  = "Hello, #{name}!"
        str  = str.upcase if loud?
        puts str
      end
    end

To make the command available on the command line, add an executable to your project calling the #execute or #run methods.

    #!usr/bin/env ruby
    require 'hello.rb'
    HelloCommand.run

If we named this file hello, set its execute flag and made it available on our systems $PATH, then:

    $ hello
    Hello, World!

    $ hello John
    Hello, John!

    $ hello --loud John
    HELLO, JOHN!

Executable can also generate help text for commands.

    $ hello --help
    USAGE: hello [options]

    Say hello.

    --loud      Say it in uppercase?
    --help      Show this message

If you look back at the class definition you can see it's pulling comments from the source to provide descriptions. It pulls the description for the command itself from the #call method.