Re: ipairs in Lua 5.3.0-alpha

[Coda Highland <chighland@...>]

On Fri, Aug 15, 2014 at 10:47 AM, Doug Currie <doug.currie@gmail.com> wrote:
> On Fri, Aug 15, 2014 at 1:16 PM, Jan Behrens
> <jbe-lua-l@public-software-group.org> wrote:
>>
>> On Fri, 15 Aug 2014 13:37:41 -0300
>> Roberto Ierusalimschy <roberto@inf.puc-rio.br> wrote:
>> [...]
>> > If the goal is only to reduce calls to length, another option would be
>> > to modify ipairs so that it stops in the first nil entry with an index
>> > larger than #t. That would have some nice properties:
>> >[...]
>>
>> It sounds like a "hack" to me.
>
>
> It is very clever. I like it.
>

I like it too!

>>
>> If we assume that nil's are allowed as values, then calling the length
>> operator here (even if it's just for a few nil elements) would require
>> the underlaying SQL library to iterate through all result rows to
>> return a length.
>
>
> No, you simply need to return the current index + 1 to continue the loop.
>

Not to mention a lot of drivers know the size of the resultset before
they start streaming records to you anyway.

/s/ Adam