hello

Quickl example: hello

This example shows how to create a really simple commandline program.

Structure

The structure it follows is simply:

#
# Short description here
#
# SYNOPSIS
#   Usage: ...
#
# OPTIONS
# #{summarized_options}
#
# DESCRIPTION
#   Long description here...
#
class SimpleCommand < Quickl::Command(__FILE__, __LINE__)

  # install options below
  options do |opt|
    # _opt_ is an OptionParser instance
  end
  
  # install the code to run the command
  def execute(args)
    # _args_ are non-option command line parameters
  end

end

# To run the command, typically in a bin/simple_command 
# shell file
SimpleCommand.run(ARGV)

Example

Try the following:

./hello 
# => Hello world!

./hello --capitalize
# => Hello World!

./hello bob
# => Hello bob!

./hello --capitalize bob
# => Hello Bob!

./hello --version
# => hello 0.1.0 (c) 2010, Bernard Lambeau

./hello --help
# => ...

./hello too many arguments
# => needless argument: too many arguments
# => hello [--help] [--version] [--capitalize] [WHO]

./hello --no-such-option 
# invalid option: --no-such-option
# hello [--help] [--version] [--capitalize] [WHO]

You have to known that ...

• An instance of command is actually executed. Therefore, it is safe to install instance variables through options and to use them in execute().
• Documentation shown with --help is the rdoc documentation evaluated in the binding of the SimpleCommand class. Therefore, you can use #{...} to display specific things (like #{summarized_options}).
• Default error handlers are installed by default to catch Interrupt, Quickl::Exit and OptionParser::Error. See error_handling example to learn more about them.