Re: [ANN] Lua 5.2.0 (work1) now available

[Alexander Gladysh <agladysh@...>]

On Sat, Jan 9, 2010 at 12:58, steve donovan <steve.j.donovan@gmail.com> wrote:
> On Sat, Jan 9, 2010 at 11:52 AM, Alexander Gladysh <agladysh@gmail.com> wrote:
>> (1) Don't have holes in tables you want to measure with #, that's all.

> Amen. But in general pack() will give you them. I agree, 'n' is a nasty hack.

> We are back in the table-with-holes thread ;)

> I am also excited about the __len metamethod.

A crazy idea: what if table.pack() would set a (pre-defined) metatable
to the tables it creates, with __len metamethod looking at n?

This is rather unusual behavior for Lua API function, but I can't see
much harm (yet), and it looks useful.

Two things would be required though: (1) "official" way access to this
metatable, since people would try to "steal" and reuse it anyway, and
(2) a flag argument for table.pack() to skip metatable setting, for
rare cases when resulting table would be reused for something
incompatible with it...

Alexander.