Re: Surprising behavior of table.insert()

[Patrick Donnelly <batrick@...>]

On Fri, Feb 25, 2011 at 4:11 PM, Axel Kittenberger <axkibe@gmail.com> wrote:
> Eitherway you should never "insert nil" into a list, if i recall
> correctly, the behavior is undefined depending on the array/hash state
> of table.

There is nothing undefined about it. The manual is quite clear:

"Inserts element value at position pos in table, shifting up other
elements to open space, if necessary. The default value for pos is
n+1, where n is the length of the table (see §2.5.5), so that a call
table.insert(t,x) inserts x at the end of table t."

There is no shifting in this case, obviously, because the given
example always appends. I think relying on *appending* nil to a table
being a no-op is entirely reasonable.

The real problem is the not passing an "x" value to insert. It should
be harmless enough to assume x is nil. After all, table.insert does
not blow up when given an explicit nil.

P.S. Please do not top-post.

-- 
- Patrick Donnelly