X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2Futf8.pm;h=5a37aecba87ccc2d8d08c3387115da0cf7d8bcc9;hb=fd20da51661b685c54940aeb116a97beabf44d0f;hp=5bec95514aa5a470204262f322b1097d4bb5be46;hpb=5463e635e29aad1605d20ed3ea9f8b3e487e0102;p=p5sagit%2Fp5-mst-13.2.git

diff --git a/lib/utf8.pm b/lib/utf8.pm
index 5bec955..5a37aec 100644
--- a/lib/utf8.pm
+++ b/lib/utf8.pm
@@ -56,10 +56,11 @@ Enabling the C<utf8> pragma has the following effect:
 
 Bytes in the source text that have their high-bit set will be treated
 as being part of a literal UTF-8 character.  This includes most
-literals such as identifiers, string constants, constant regular
-expression patterns and package names.  On EBCDIC platforms characters
-in the Latin 1 character set are treated as being part of a literal
-UTF-EBCDIC character.
+literals such as identifier names, string constants, and constant
+regular expression patterns.
+
+On EBCDIC platforms characters in the Latin 1 character set are
+treated as being part of a literal UTF-EBCDIC character.
 
 =back
 
@@ -77,15 +78,22 @@ The following functions are defined in the C<utf8::> package by the perl core.
 
 =item * $num_octets = utf8::upgrade($string);
 
-Converts internal representation of string to the Perl's internal
+Converts (in-place) internal representation of string to Perl's internal
 I<UTF-X> form.  Returns the number of octets necessary to represent
-the string as I<UTF-X>.  Note that this should not be used to convert
+the string as I<UTF-X>.  Can be used to make sure that the
+UTF-8 flag is on, so that C<\w> or C<lc()> work as expected on strings
+containing characters in the range 0x80-0xFF.  Note that this should
+not be used to convert
 a legacy byte encoding to Unicode: use Encode for that.  Affected
 by the encoding pragma.
 
-=item * utf8::downgrade($string[, CHECK])
+=item * utf8::downgrade($string[, FAIL_OK])
 
-Converts internal representation of string to be un-encoded bytes.
+Converts (in-place) internal representation of string to be un-encoded
+bytes.  Returns true on success. On failure dies or, if the value of
+FAIL_OK is true, returns false.  Can be used to make sure that the
+UTF-8 flag is off, e.g. when you want to make sure that the substr()
+or length() function works with the usually faster byte algorithm.
 Note that this should not be used to convert Unicode back to a legacy
 byte encoding: use Encode for that.  B<Not> affected by the encoding
 pragma.
@@ -93,15 +101,16 @@ pragma.
 =item * utf8::encode($string)
 
 Converts (in-place) I<$string> from logical characters to octet
-sequence representing it in Perl's I<UTF-X> encoding.  Note that this
-should not be used to convert a legacy byte encoding to Unicode: use
-Encode for that.
+sequence representing it in Perl's I<UTF-X> encoding. Same as
+Encode::encode_utf8(). Note that this should not be used to convert
+a legacy byte encoding to Unicode: use Encode for that.
 
 =item * $flag = utf8::decode($string)
 
 Attempts to convert I<$string> in-place from Perl's I<UTF-X> encoding
-into logical characters.  Note that this should not be used to convert
-Unicode back to a legacy byte encoding: use Encode for that.
+into logical characters. Same as Encode::decode_utf8(). Note that this
+should not be used to convert Unicode back to a legacy byte encoding:
+use Encode for that.
 
 =item * $flag = utf8::valid(STRING)
 
@@ -113,12 +122,28 @@ state.
 
 =back
 
-C<utf8::encode> is like C<utf8::upgrade>, but the UTF8 flag is cleared.
-See L<perlunicode> for more on the UTF8 flag and the C API functions
-C<sv_utf8_upgrade>, C<sv_utf8_downgrade>, C<sv_utf8_encode>,
+C<utf8::encode> is like C<utf8::upgrade>, but the UTF8 flag is
+cleared.  See L<perlunicode> for more on the UTF8 flag and the C API
+functions C<sv_utf8_upgrade>, C<sv_utf8_downgrade>, C<sv_utf8_encode>,
 and C<sv_utf8_decode>, which are wrapped by the Perl functions
 C<utf8::upgrade>, C<utf8::downgrade>, C<utf8::encode> and
-C<utf8::decode>.
+C<utf8::decode>.  Note that in the Perl 5.8.0 implementation the
+functions utf8::valid, utf8::encode, utf8::decode, utf8::upgrade,
+and utf8::downgrade are always available, without a C<require utf8>
+statement-- this may change in future releases.
+
+=head1 BUGS
+
+One can have Unicode in identifier names, but not in package/class or
+subroutine names.  While some limited functionality towards this does
+exist as of Perl 5.8.0, that is more accidental than designed; use of
+Unicode for the said purposes is unsupported.
+
+One reason of this unfinishedness is its (currently) inherent
+unportability: since both package names and subroutine names may need
+to be mapped to file and directory names, the Unicode capability of
+the filesystem becomes important-- and there unfortunately aren't
+portable answers.
 
 =head1 SEE ALSO