constants: you cannot use variables in them. if you want similar
run-time functionality, use C<chr()> and C<charnames::vianame()>.
-Also note that if all the code points for pack "U" are below 0x100,
-bytes will be generated, just like if you were using C<chr()>.
-
- my $bytes = pack("U*", 0x80, 0xFF);
-
If you want to force the result to Unicode characters, use the special
C<"U0"> prefix. It consumes no arguments but forces the result to be
in Unicode characters, instead of bytes.
- my $chars = pack("U0U*", 0x80, 0xFF);
+ my $chars = pack("U0C*", 0x80, 0xFF);
+
+Likewise, you can force the result to be bytes by using the special
+C<"C0"> prefix.
=head2 Handling Unicode