Treatment of negative index to select()

[Doug Rogers <douglua@...>]

Since 5.2 is still undergoing change, I'm wondering if the authors would 
consider changing the (not well documented) behavior of select() for 
negative indexes?

The manual [1] states that select returns all arguments above the first 
index, but doesn't say that negative arguments are treated in any 
special way. The actual behavior in 5.1.4 is similar to that of string 
indexing, which I can certainly understand.

But some interesting and useful behaviors can be supported if select() 
were allowed to return the arguments up to the absolute value of the 
index when the index is negative. Or perhaps some other means could be 
provided to select the first n items.

See [2]. That message is long, inviting a cold reception, but it does 
have the advantage of putting everything in one place! FYI, the patch is 
against 5.1.4.

Regardless, there seems to be an inconsistency in handling overflow of a 
numeric argument. An index which is too large is accepted as referring 
to the last element whereas an index that is too small (too negative) is 
rejected rather than being accepted as the first element.

Doug

[1] http://www.lua.org/manual/5.1/manual.html#pdf-select
[2] http://lua-users.org/lists/lua-l/2009-01/msg00137.html