Commander

Command-line interface builder for the Crystal programming language.

Installation

Add this to your application's shard.yml:

dependencies:
  commander:
    github: mrrooijen/commander
    version: ~> 0.4.0

Usage

Almost everything you need to know in one example.

Refer to the Features section below for a list of all available features.

require "commander"

cli = Commander::Command.new do |cmd|
  cmd.use  = "my_program"
  cmd.long = "my program's (long) description."

  cmd.flags.add do |flag|
    flag.name        = "env"
    flag.short       = "-e"
    flag.long        = "--env"
    flag.default     = "development"
    flag.description = "The environment to run in."
  end

  cmd.flags.add do |flag|
    flag.name        = "port"
    flag.short       = "-p"
    flag.long        = "--port"
    flag.default     = 8080
    flag.description = "The port to bind to."
  end

  cmd.flags.add do |flag|
    flag.name        = "timeout"
    flag.short       = "-t"
    flag.long        = "--timeout"
    flag.default     = 29.5
    flag.description = "The wait time before dropping the connection."
  end

  cmd.flags.add do |flag|
    flag.name        = "verbose"
    flag.short       = "-v"
    flag.long        = "--verbose"
    flag.default     = false
    flag.description = "Enable more verbose logging."
    flag.persistent  = true
  end

  cmd.run do |options, arguments|
    options.string["env"]    # => "development"
    options.int["port"]      # => 8080
    options.float["timeout"] # => 29.5
    options.bool["verbose"]  # => false
    arguments                # => Array(String)
    puts cmd.help            # => Render help screen
  end

  cmd.commands.add do |cmd|
    cmd.use   = "kill <pid>"
    cmd.short = "Kills server by pid."
    cmd.long  = cmd.short
    cmd.run do |options, arguments|
      arguments # => ["62719"]
    end
  end
end

Commander.run(cli, ARGV)

Here's what the help page looks like for this configuration:

$ my_program help

my_program - my program's (long) description.

Usage:
  my_program [command] [flags] [arguments]

Commands:
  help [command]  Help about any command.
  kill <pid>      Kills server by pid.

Flags:
  -e, --env      The environment to run in. default: 'development'
  -h, --help     Help for this command.
  -p, --port     The port to bind to. default: 8080
  -t, --timeout  The wait time before dropping the connection. default: 29.5
  -v, --verbose  Enable more verbose logging.

This is how you override the default options and pass in additional arguments:

$ my_program -ve production --port 8443 --timeout=25 arg1 arg2 arg3 -- arg4 --arg5

cmd.run do |options, arguments|
  options.string["env"]    # => "production"
  options.int["port"]      # => 8443
  options.float["timeout"] # => 25.0
  options.bool["verbose"]  # => true
  arguments                # => ["arg1", "arg2", "arg3"]
end

Features

• Define commands recursively
• Define flags on a per-command basis
  • Short argument flags (-p 8080)
  • Short boolean flags (-f)
  • Multi-short flags (-fp 8080, equivalent to -f -p 8080)
  • Long argument flags (--port 8080, --port=8080)
  • Long boolean flags (--force)
  • Share flags with multiple commands (verbose = Commander::Flag.new)
  • Persistent flags for recursively inheriting flags from a parent command (flag.persistent = true)
  • Global flags by defining persistent flags on the root command (flag.persistent = true)
  • Default values for each flag
  • Automatically validates, parses and casts to the correct type
    • Automatically passes all parsed options to cmd.run
• Receive additional cli arguments per command (arguments in cmd.run)
• Receive unmapped flags as arguments (cmd.ignore_unmapped_flags = true)
• Receive all input after -- as arguments
• Automatically generates a help page for each command
  • Generates a help command for each command to access the help page
  • Generates -h, --help flags for each command to access to help page
• Provide Commander.run(cli, ARGV) to handle end-user input exceptions.

File Structure and Testing

Refer to this answer.

Contributing

1. Fork it ( https://github.com/mrrooijen/commander/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