On Wed, Jun 29, 2011 at 12:25 AM, Lorenzo Donati
<lorenzodonatibz@interfree.it> wrote:

* 1st point
Section 3.4.6 of Lua 5.2 refman says:
"Unless a __len metamethod is given, the length of a table t is only defined
if the table is a sequence, that is, the set of its positive numeric keys is
equal to {1..n} for some integer n."

...

"Note, however, that non-numeric keys *or non-positive numeric keys* do not interfere with whether a table is a sequence."

Wouldn't you also want to list keys of zero and positive integer keys> n+1?
Its just a note, it doesn't have to be an exhaustive description of
the complement of the set of positive integers from {1...n}.

...

Therefore I would modify slightly the definition:
"Unless a __len metamethod is given, the length of a table t is only defined
if the table is a sequence, that is, the set of its positive numeric keys is
equal to {1..n} for some *non-negative* integer n."
This would rule out that (admittedly unintuitive, but correct)
misinterpretation.

In the set of positive keys {1..n}, how could it be correct to think n
is not positive?