Re: Lookup nil table index

[Michael Wolf <miwo@...>]

Hello,

> I'm working on code with quite deep tables. When referring to an element
> in the table, I use the table keys joined by dots, eg:
>
> 	a = thing.foo.bar.this.that
>
> When one of the indicated elements does not exist, an error is generated
> for apperent reasons: attempt to index nil value.

I use a little function to do the deep table lookup, if a key could be nil:

--returns object indexed by 1..n keys
--returns nil if a key is nil
function indextbl(obj,...)
	local idx={...}
	for i=1,select('#',...) do
		local k=idx[i]
		if obj==nil or k==nil then
			return nil
		else
			obj=rawget(obj,k)
		end
	end
	return obj
end

You can use it as follows:
a = indextbl(thing,'foo','bar','this','that')

BR,
Michael