Re: Lookup nil table index
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- Subject: Re: Lookup nil table index
- From: Michael Wolf <miwo@...>
- Date: 2006年11月30日 20:25:39 +0100
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