$utf8::hint_bits = 0x00800000;
-our $VERSION = '1.00';
+our $VERSION = '1.03';
sub import {
$^H |= $utf8::hint_bits;
use utf8;
no utf8;
+ # Convert a Perl scalar to/from UTF-8.
+ $num_octets = utf8::upgrade($string);
+ $success = utf8::downgrade($string[, FAIL_OK]);
+
+ # Change the native bytes of a Perl scalar to/from UTF-8 bytes.
+ utf8::encode($string);
+ utf8::decode($string);
+
+ $flag = utf8::is_utf8(STRING); # since Perl 5.8.1
+ $flag = utf8::valid(STRING);
+
=head1 DESCRIPTION
The C<use utf8> pragma tells the Perl parser to allow UTF-8 in the
This pragma is primarily a compatibility device. Perl versions
earlier than 5.6 allowed arbitrary bytes in source code, whereas
in future we would like to standardize on the UTF-8 encoding for
-source text. Until UTF-8 becomes the default format for source
-text, this pragma should be used to recognize UTF-8 in the source.
-When UTF-8 becomes the standard source format, this pragma will
-effectively become a no-op. For convenience in what follows the
-term I<UTF-X> is used to refer to UTF-8 on ASCII and ISO Latin based
-platforms and UTF-EBCDIC on EBCDIC based platforms.
+source text.
+
+B<Do not use this pragma for anything else than telling Perl that your
+script is written in UTF-8.> The utility functions described below are
+useful for their own purposes, but they are not really part of the
+"pragmatic" effect.
+
+Until UTF-8 becomes the default format for source text, either this
+pragma or the L</encoding> pragma should be used to recognize UTF-8
+in the source. When UTF-8 becomes the standard source format, this
+pragma will effectively become a no-op. For convenience in what
+follows the term I<UTF-X> is used to refer to UTF-8 on ASCII and ISO
+Latin based platforms and UTF-EBCDIC on EBCDIC based platforms.
+
+See also the effects of the C<-C> switch and its cousin, the
+C<$ENV{PERL_UNICODE}>, in L<perlrun>.
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
UTF-8. If you want to have such bytes and use utf8, you can disable
utf8 until the end the block (or file, if at top level) by C<no utf8;>.
+If you want to automatically upgrade your 8-bit legacy bytes to UTF-8,
+use the L</encoding> pragma instead of this pragma. For example, if
+you want to implicitly upgrade your ISO 8859-1 (Latin-1) bytes to UTF-8
+as used in e.g. C<chr()> and C<\x{...}>, try this:
+
+ use encoding "latin-1";
+ my $c = chr(0xc4);
+ my $x = "\x{c5}";
+
+In case you are wondering: yes, C<use encoding 'utf8';> works much
+the same as C<use utf8;>.
+
=head2 Utility functions
-The following functions are defined in the C<utf8::> package by the perl core.
+The following functions are defined in the C<utf8::> package by the
+Perl core. You do not need to say C<use utf8> to use these and in fact
+you should not say that unless you really want to have UTF-8 source code.
=over 4
-=item * $num_octets = utf8::upgrade($string);
+=item * $num_octets = utf8::upgrade($string)
-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>. Can be used to make sure that the
+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>. 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.
+containing characters in the range 0x80-0xFF (oon ASCII and
+derivatives). 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[, FAIL_OK])
+=item * $success = utf8::downgrade($string[, FAIL_OK])
-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
+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
=item * utf8::encode($string)
-Converts (in-place) I<$string> from logical characters to octet
-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.
+Converts in-place the octets of the I<$string> to the octet sequence
+in Perl's I<UTF-X> encoding. Returns nothing. B<Note that this does
+not change the "type" of I<$string> to UTF-8>, and that this handles
+only ISO 8859-1 (or EBCDIC) as the source character set. Therefore
+this should not be used to convert a legacy 8-bit encoding to Unicode:
+use Encode::decode() for that. In the very limited case of wanting to
+handle just ISO 8859-1 (or EBCDIC), you could use utf8::upgrade().
-=item * $flag = utf8::decode($string)
+=item * utf8::decode($string)
Attempts to convert I<$string> in-place from Perl's I<UTF-X> encoding
-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.
+into octets. Returns nothing. B<Note that this does not change the
+"type" of <$string> from UTF-8>, and that this handles only ISO 8859-1
+(or EBCDIC) as the destination character set. Therefore this should
+not be used to convert Unicode back to a legacy 8-bit encoding:
+use Encode::encode() for that. In the very limited case of wanting
+to handle just ISO 8859-1 (or EBCDIC), you could use utf8::downgrade().
+
+=item * $flag = utf8::is_utf8(STRING)
+
+(Since Perl 5.8.1) Test whether STRING is in UTF-8. Functionally
+the same as Encode::is_utf8().
=item * $flag = utf8::valid(STRING)
-[INTERNAL] Test whether STRING is in a consistent state. Will return
-true if string is held as bytes, or is well-formed UTF-8 and has the
-UTF-8 flag on. Main reason for this routine is to allow Perl's
-testsuite to check that operations have left strings in a consistent
-state.
+[INTERNAL] Test whether STRING is in a consistent state regarding
+UTF-8. Will return true is well-formed UTF-8 and has the UTF-8 flag
+on B<or> if string is held as bytes (both these states are 'consistent').
+Main reason for this routine is to allow Perl's testsuite to check
+that operations have left strings in a consistent state. You most
+probably want to use utf8::is_utf8() instead.
=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>. The functions utf8::valid, utf8::encode,
-utf8::decode, utf8::upgrade, and utf8::downgrade are always available,
-without a C<require utf8> statement.
+C<utf8::decode>. Note that in the Perl 5.8.0 and 5.8.1 implementation
+the functions utf8::is_utf8, 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
-L<perlunicode>, L<bytes>
+L<perluniintro>, L<encoding>, L<perlrun>, L<bytes>, L<perlunicode>
=cut
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