Re: C API - lua_next traversal of "array" table

["Soni L." <fakedme@...>]

On 22/08/16 05:43 AM, Viacheslav Usov wrote:
> On Sat, Aug 20, 2016 at 10:09 AM, Tim Hill <drtimhill@gmail.com 
> <mailto:drtimhill@gmail.com>> wrote:
>
> > Incorrect. The definition defines if a table is ALSO a sequence. It 
> does say it must ONLY be a sequence.
>
> I did misinterpret what the definition said, but you also did it here. 
> What that really means is that we simply do not have a well-defined 
> concept of "array" in Lua. So let's define it.
>
> A table has an /array part/ if it has a subset of keys that is {1 .. 
> n} for some positive integer n, with corresponding non-nil values; 
> those keys and their values are the array part.

A table doesn't have an array part because my implementation uses linked 
lists.

> A sequence is a table that has an array part. A sequence that is equal 
> to its array part is an /array/. A sequence whose keys that are not in 
> its array part are not numbers is /regular/.
>
> The length operator # has an intuitive and unsurprising meaning only 
> when applied to arrays. The length operator can still be used 
> coherently with regular sequences. Its use against other kinds of 
> tables should, in my opinion, be avoided.
>
> Cheers,
> V.

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