Re: tinsert (was: Finding the version)

[Reuben Thomas <rrt@...>]

> > > Be careful: to correctly implement tinsert in Lua using the C tinsert you must pass the correct number of parameters to the C
> > > function, like in
> > >
> > > function tinsert(t, n, v)
> > >       if (v) then
> > >               %tinsert(t, n, v)
> > >       else
> > >               %tinsert(t, n)
> > >       end
> > > end
> >
> > Sorry, I meant that. The version I posted was an incorrect "optimisation"!
>
> Even that is not correct.  The original tinsert when called with a nil third
> argument will insert that nil into the table.

i.e. it will increment n. Hmm...
>
> Compatible (fixed) version would be:
>
>   function tinsert(t, ...)
>     if arg.n == 1 then
>       %tinsert(t, arg[1])
>     elseif arg.n == 2 then

I'd prefer

      elseif arg.n >= 2 then
        %tinsert(t, arg[1], arg[2])
      elseif t then
        %tinsert(t) -- let the implementation generate the error
      else
        %tinsert() -- let the C implementation generate the error
      end

...which works fine with extra args, and lets the C implementation generate
the error for one or zero args. The difference between passing one and zero
args is perhaps a bit fussy, though.

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