Unicode aware module

Can I write a unicode aware function that behaves differently
depending on whether utf8 is in scope for its caller?  If not, any
plans to support this?


   sub foo {
      if (IN_UTF8(caller)) {
          # deal with UTF8
      } else {
          # something different
      }
   }

   foo();
   use utf8;
   foo();

[I'm investigating ways to add UTF-8 support to HTML::Entities.]

Regards,
Gisle