BEGIN {
   eval { require Cache::File }
      or warn("Proceeding without Cache::File\n");

   Cache::File->import(qw( ... ))
      if Cache::File->can("import");
}

##</code><code>##

BEGIN {
   my @imports = qw( ... );

   eval "use Cache::File \@imports"
      or warn("Proceeding without Cache::File\n");
}