Re: [ANN] Lua 5.3.0 (alpha) now available

[Philipp Janda <siffiejoe@...>]

Hi!

Am 31.07.2014 20:30 schröbte Luiz Henrique de Figueiredo:
> Lua 5.3.0 (alpha) is now available for testing at
> 	http://www.lua.org/work/lua-5.3.0-alpha.tar.gz
>
> All feedback welcome. Thanks.
> --lhf
I think I spotted a formatting error in the manual (`id{__ipairs}` in 
the "Changes in the Libraries" section).
I really like that many table operations now respect metamethods, but 
now starts the complaining:
Is there a reason why the protocol for `ipairs` has changed from 
"iterate to first nil value" to "iterate to #table"? The first is well 
defined for all tables, and runs in O(n), while the second needs 
O(nlog(n)) time, requires a proper sequence for defined behavior, or can 
yield nil values during iteration.
If this behavior is going to stay, I also think the metamethod check can 
be simplified to
    lua_CFunction iter =
        (luaL_getmetafield(L, 1, "__len"))
           ? ipairsaux : ipairsaux_raw;

I.e. `__index` will never trigger unless there is a hole in the table in 
which case you need `__len` as well for the iteration to have defined 
behavior.

Philipp