Re: table.unpack(...) and the __index metamethod

[Tim Hill <drtimhill@...>]

On Jun 14, 2014, at 3:25 AM, Dirk Laurie <dirk.laurie@gmail.com> wrote:

> 2014-06-14 8:27 GMT+02:00 Tim Hill <drtimhill@gmail.com>:
>> 
>> Anyway, I’m not tied to this but I still think the OP had
>> a good point. The Lua ref notes in a couple of places
>> the raw accesses are done for speed, but he is correct
>> in noting that you don’t need to sacrifice non-raw access
>> for speed in this case.
>> 
> 
> The manual (which anyway refers you to other places for
> the decisions behind the design of Lua) only says "For
> performance reasons", true, but that is not the only reason.
> 
> You can't have one rule for concat and unpack and another
> rule for insert, remove and sort. But for the mutable table
> functions, semantics becomes a mare's nest unless you
> have raw access.
> 

Well you CAN have different rules, whether you want to or not is a different matter. Since table.unpack() doesn’t mutate the table I don’t see any real problem.

As for mutable table functions, I’m not sure I see the mare’s nest you do, but that’s not the issue here.

As I said, the stated reason for not having metamethod access during unpack doesn’t seem to be necessary. I can’t comment on “unstated” reasons, since they are unstated :)

—Tim