If you are using a Windows machine and your function is in a DLL, you could also use Win32::API:

use Win32::API ();

my $Get_Temperature = Win32::API->new(
   'mydll', 'float Get_Temperature()',
);

my $isThisHot = Win32::API->new(
   'mydll', 'BOOL isThisHot(int)',
);

my $temp = $Get_Temperature->Call();
my $hot  = $isThisHot->Call($temp);
[download]

or

use Win32::API ();

Win32::API->Import('mydll', 'float Get_Temperature()');
Win32::API->Import('mydll', 'BOOL isThisHot(int)');

my $temp = Get_Temperature();
my $hot  = isThisHot($temp);
[download]