If the aim is to create a temporary file name (quite slow method):

use Time::HiRes qw(gettimeofday);

my $rand = \&gettimeofday;
my $temp_file_name = sub{ int(rand($rand->())) };

$temp_file_name = sub{ 
       local $.; 
       $..= $temp_file_name->() 
          for 1..5; 
       return $.;
}->();
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