Some small requests for the next release

[nt <niklas@...>]

Hello,

A request for a few small additions to the next release. Forgive me if 
the features are already available--I am using an older 5.0.

1) Add 'math.nan' as a constant to the math library.  At the moment, the 
"feature" of doing
      local nan = tonumber("nan")
   works, but is inconvenient, probably non portable and hard to 
remember.  Inclusion of the
       if v ~= v then ---is nan
   mechanism in the reference manual  would also be nice in lieu of a 
math.isnan
   Obviously issues arise when numbers are not reals---I suppose 
something such as MAXINT could
    be returned for the integer case.

2) Perhaps I am missing something, but there does not appear to be a 
convenient way to determine if a
   table is empty.  Perhaps a 'table.isEmpty(t)' function could be 
added or even
    local arraysize,haveHashes = table.stats(t)
   which would reveal something about the internals of the table (i.e. 
how much is allocated to array
    and whether it is a pure array). Handy for estimating likely heap 
size in test situations.

3) Some way to access file handles in C code.  At the moment I have to 
look at the io library source
   and see that the file handle userdata is a "FILE*" and put in check 
and caste code accordingly.
   Probably not portable in general.  Something like 
'luaL_tofilehandle(L, arg)' might be helpful.

4) The issue of accessing nested tables comes up on a regular basis. 
Doing so in the API is tedious, so
    I am sure everyone has rolled their own equivalent of:
           lua_gettablepath(L, arg, "key1", "key2", ..., NULL)
    using varargs.  Would be nice to standardize this as a convenience 
function.

5) Please, please add a section to the Reference Manual documenting the 
functions in lauxilib.h. Would
    make it much easier to get up to speed on what routines are 
available.  While I am on the subject,
    it would also be nice if this was called 'luaaux.h' or something 
with 'lua' at the front as that would
    lessen the likelihood of collisions with other e.g. Linux include 
files in future OS releases.  Even
    better would be something like:
         #include <lua/core.h>
         #include <lua/lib.h>
         #include <lua/aux.h>
    but that is rather Unix specific and makes it a little harder to 
have competing versions installed.

thanks,
niklas