[Encode] "\x{df}" is NOT UTF-8 (Was: [Re: Encode anomalies ...)

[Dan Kogai]

On Saturday, March 30, 2002, at 04:57 , Andreas J. Koenig wrote:
> All the warnings below seem bogus to me.
>
>     % /usr/local/perl-5.7.3@15620/bin/perl -wle '
>     use Encode qw(from_to);
>     $x = "\x{df}";
>     from_to($x,"utf-8","iso8859-1");
>     '
>     Use of uninitialized value in subroutine entry at 
> /usr/local/perl-5.7.3@15620/lib/5.7.3/i686-linux-thread-multi/Encode.pm 
> line 200.
>     Use of uninitialized value in subroutine entry at 
> /usr/local/perl-5.7.3@15620/lib/5.7.3/i686-linux-thread-multi/Encode.pm 
> line 200.
> [snip]

   I was confused with this one until I have read it thought till the end 
of your report.  "\x{df}" is NOT UTF-8!  Let's see this one one more 
time.

use Encode qw(encode_utf8 from_to);
$x = encode_utf8("\x{df}");
from_to($x,"utf-8","iso8859-1");

   And the following will warn like this;

  "\N{U+100}" does not map to iso-8859-1 at 
/usr/home/dankogai/work/Encode/blib/lib/Encode.pm line 200.
Use of uninitialized value in length at 
/usr/home/dankogai/work/Encode/blib/lib/Encode.pm line 202.

   The first one is a good, informative warning but the second one is not.
   It is encode() that is warning.  The following pseudo-diff-u will fix 
it.

  sub from_to
  {
      my ($string,$from,$to,$check) = @_;
      my $f = find_encoding($from);
      croak("Unknown encoding '$from'") unless defined $f;
      my $t = find_encoding($to);
      croak("Unknown encoding '$to'") unless defined $t;
      my $uni = $f->decode($string,$check);
      return undef if ($check && length($string));
      $string = $t->encode($uni,$check);
      return undef if ($check && length($uni));
-    return length($_[0] = $string);
+    return defined($_[0] = $string) ? length($string) : undef ;
  }

I have also added documents on the return value of from_to()
But "raw" "\x{}" is beyond my cap.  Any suggestions?  NI-S? jhi?

Dan the Encode Maintainer