parsing-command-line-options.rb

USAGE = <<ENDUSAGE
Usage:
   docubot [-h] [-v] [create [-s shell] [-f]] directory [-w writer] [-o output_file] [-n] [-l log_file]
ENDUSAGE

HELP = <<ENDHELP
   -h, --help       Show this help.
   -v, --version    Show the version number (#{DocuBot::VERSION}).
   create           Create a starter directory filled with example files;
                    also copies the template for easy modification, if desired.
   -s, --shell      The shell to copy from.
                    Available shells: #{DocuBot::SHELLS.join(', ')}
   -f, --force      Force create over an existing directory,
                    deleting any existing files.
   -w, --writer     The output type to create [Defaults to 'chm']
                    Available writers: #{DocuBot::Writer::INSTALLED_WRITERS.join(', ')}
   -o, --output     The file or folder (depending on the writer) to create.
                    [Default value depends on the writer chosen.]
   -n, --nopreview  Disable automatic preview of .chm.
   -l, --logfile    Specify the filename to log to.

ENDHELP

ARGS = { :shell=>'default', :writer=>'chm' }
UNFLAGGED_ARGS = [ :directory ]
next_arg = UNFLAGGED_ARGS.first
ARGV.each{ |arg|
	case arg
		when '-h','--help'      then ARGS[:help]      = true
		when 'create'           then ARGS[:create]    = true
		when '-f','--force'     then ARGS[:force]     = true
		when '-n','--nopreview' then ARGS[:nopreview] = true
		when '-v','--version'   then ARGS[:version]   = true
		when '-s','--shell'     then next_arg = :shell
		when '-w','--writer'    then next_arg = :writer
		when '-o','--output'    then next_arg = :output
		when '-l','--logfile'   then next_arg = :logfile
		else
			if next_arg
				ARGS[next_arg] = arg
				UNFLAGGED_ARGS.delete( next_arg )
			end
			next_arg = UNFLAGGED_ARGS.first
	end
}

if ARGS[:version]
	puts "DocuBot v#{DocuBot::VERSION}"
end

if ARGS[:help] or !ARGS[:directory]
	puts USAGE unless ARGS[:version]
	puts HELP if ARGS[:help]
	exit
end

if ARGS[:logfile]
	$stdout.reopen( ARGS[:logfile], "w" )
	$stdout.sync = true
	$stderr.reopen( $stdout )
end