Re: How to getopt?

[Axel Kittenberger <axkibe@...>]

When called by the lua standalone, the arguments are stored in "arg".
IMHO a "high order" language like lua does not need a getopt library,
as this is pretty easy to do yourself, and you do not need additional
requirements.

This for example is a simplified case of my use, searches for all
options starting with a "-", it does not care about short opts, there
are long opts only. and all options not part  of a "-" is stored in
"nonopts" for later parsing.

-- first argument if number of arguments the option takes, second the
function to handle them.
local options = {
	logfile  = {1, function(file) settings.logfile = file end},
	nodaemon = 	{0, function() settings.nodaemon=true end},
	-- etc.
}
-- nonopts is filled with all args that were no part dash options
local nonopts = {}
local i = 1
while i <= #arg do
	local a = args[i]
	if a:sub(1, 1) ~= "-" then
		table.insert(nonopts, args[i])
	else
		if a:sub(1, 2) == "--" then
			a = a:sub(3)
		else
			a = a:sub(2)
		end
		local o = options[a]
		if not o then
			print("unknown option command line option: ", a)
			os.exit(-1)
		end
		if o[1] >= 0 and i + o[1] > #args then
			print"Error",a," needs ",o[1]," arguments")
			os.exit(-1)
		end
		-- this is a bit dirty, I have no more than 3 args ever, and was too
lazy to think of general code.
		-- a more generic solution would build a list and call the function
with unpack(list)
		if o[2] then
			if o[1] == 0 then
				o[2]()
			elseif o[1] == 1 then
				o[2](args[i + 1])
			elseif o[1] == 2 then
				o[2](args[i + 1], args[i + 2])
			elseif o[1] == 3 then
				o[2](args[i + 1], args[i + 2], args[i + 3])
			end
		end
		i = i + o[1]
	end
	i = i + 1
end

--- care about your nonopts here

On Thu, Dec 23, 2010 at 1:49 AM, Steve Litt <slitt@troubleshooters.com> wrote:
> Hi all,
>
> I'm rewriting my UMENU program
> (http://www.troubleshooters.com/umenu/index.htm) in Lua, and so far so good.
> So far, I see little reason to ever use Perl again :-)
>
> UMENU uses Perl's getopt_long. I've read all sorts of things about Lua's
> Getopt facility, and so far it seems like yes, there's one in the standard
> package, but some are saying it doesn't work all that well and a lot of people
> are writing their own getopt facilities.
>
> Ideally, I'd like my Lua based UMENU to work with plain, ordinary, everyone
> can install it Lua, rather than depending on special packages the user needs
> to install, so if the one in the standard library works, that's what I'd like
> to use. I could also just manually check for arguments -- there aren't that
> many options to UMENU.
>
> So what are you all using for Getopt or preferably Getopt_long in Lua?
>
> Thanks
>
> SteveT
>
> Steve Litt
> Recession Relief Package
> http://www.recession-relief.US
> Twitter: http://www.twitter.com/stevelitt
>
>
>