File::TempDir would be a good name.

an approach like FindBin.pm, e.g.
   use File::TempDir qw($TempDir);
   print "Correct temporary directory in the $^O OS is $TempDir\n";

Makefile

  I've received this message, help me make complete the list of sure UNIX OS.
  Here are the "osname"s that I found in perl's Configure script:
    aix apollo bsd386 dcosx dec_osf dgux dnix dynix dynixptx esix fps
    freebsd genix hp_osf1 hpux irix isc linux lynxos machten minix mips
    mips_osf1 netbsd newsos newsos4 next os2 powerux qnx sco sco_xenix
    solaris sunos svr4 sysv titanos ultrix umips unicos unicosmk uts
  The ones which I am sure are "unix" systems are:
    aix bsd386 dec_osf dgux freebsd hp_osf1 hpux irix linux mips_osf1
    netbsd next sco sco_xenix solaris sunos svr4 sysv ultrix uts
  I also suspect that these are "unix", but I'm not certain:
    dcosx dnix dynix dynixptx esix fps genix isc lynxos machten
    minix mips newsos newsos4 powerux qnx titanos umips unicos  unicosmk
  I'm completely uncertain about "apollo" (is that their "Domain" OS?).
    And "os2" is right out.

Develop a correct MacOS check routine
The system's temporary directory is in in system folder, and the 
name is localized, so it depends on 1) the name of the disk and 2) 
the system version.It is not uncommon that users move or rename it either.
There are mac specific modules to find it, but I don't think 
everybody uses them...macintosh hd:desktop folder:temp
might work, but only if that temp directory is created if it doesn't exist
and only if the user has named his/her hard drive "macintosh hd"
>Does $ENV{TMPDIR} work on MacOS?
There are no %ENV on macs, but MacPerl provides a rather simple way to add them.
I would however not assume they are there, but you could test for it
