Re: Incorrect args for unary minus

["Aaron Brown" <arundelo@...>]

Mark Gossage wrote:

> function printargs(...) table.foreach({...},print) end
> clss={}
> mt={__unm=printargs}
> setmetatable(clss,mt)
> a=-clss
>
> It reports that there are in fact two arguments (the table
> repeated twice).

> Is the manual wrong, or is there a bug in the code?

It looks like this happens because the function Arith in
lvm.c doesn't have a special case for the one unary
arithmetical operator.  This of course is not a problem
unless you write a unary minus metamethod that looks for a
second argument, which you probably shouldn't do.

The Lua team can answer whether they consider this a bug (in
the manual or the implementation).

--
Aaron
http://arundelo.com/