--[[
Module that returns one value from a list of unnamed parameters
Named parameter idx is the index of the parameter that is to be returned
Negative indices count backward from the end of the list
==]]
local p = {}
p.getVal = function(frame)
local args = {}
-- copy arguments from frame object and its parent
for k, v in pairs(frame.args) do
args[k] = v
end
for k, v in pairs(frame:getParent().args) do
args[k] = v
end
if not args[1] then
return nil
end
local idx = tonumber(args.idx) or 1
if idx < 0 then idx = #args + idx + 1 end
return args[idx]
end
return p
