Re: Just curious: Why is tonumber(nil) not 0?

[Luiz Henrique de Figueiredo <lhf@...>]

> I was briefly caught by doing this test:
> 
>     if tonumber(something) > 0 then
>        ...
>     end
> 
> with something=nil. 
> 
> I'm not advocating a change, but what's the thought-process behind this 
> behavior?  Wouldn't you consider the numeric value of nil to be 0?

The current behavior is useful to catch typos:
	myNumber = "123.456"
	print(tonumber(mynumber))	-- note typo

If you really need the numeric value of nil to be 0 just redefine tonumber:
	do
		local _tonumber=tonumber
		function tonumber(x)
			if x==nil then return 0 else return _tonumber(x) end
		end
	end

If tonumber supported a __tonumber metamethod, this could be simpler.