2 our $VERSION = do { my @r = (q$Revision: 1.28 $ =~ /\d+/g); sprintf "%d."."%02d" x $#r, @r };
10 Carp::croak "encoding pragma does not support EBCDIC platforms";
14 our $HAS_PERLIO_ENCODING;
16 eval { require PerlIO::encoding; };
18 $HAS_PERLIO_ENCODING = 0;
20 $HAS_PERLIO_ENCODING = 1;
28 $name ||= $ENV{PERL_ENCODING};
30 my $enc = find_encoding($name);
31 unless (defined $enc) {
33 Carp::croak "Unknown encoding '$name'";
35 unless ($arg{Filter}){
36 ${^ENCODING} = $enc; # this is all you need, actually.
37 $HAS_PERLIO_ENCODING or return 1;
38 for my $h (qw(STDIN STDOUT)){
40 unless (defined find_encoding($arg{$h})) {
42 Carp::croak "Unknown encoding for $h, '$arg{$h}'";
44 eval qq{ binmode($h, ":encoding($arg{$h})") };
46 unless (exists $arg{$h}){
47 eval qq{ binmode($h, ":encoding($name)") };
56 defined(${^ENCODING}) and undef ${^ENCODING};
58 require Filter::Util::Call ;
59 Filter::Util::Call->import ;
64 if (($status = filter_read()) > 0){
65 $_ = $enc->decode($_, 1);
71 # warn "Filter installed";
73 return 1; # I doubt if we need it, though
81 if ($INC{"Filter/Util/Call.pm"}){
82 eval { filter_del() };
92 encoding - allows you to write your script in non-asii or non-utf8
96 use encoding "greek"; # Perl like Greek to you?
97 use encoding "euc-jp"; # Jperl!
99 # or you can even do this if your shell supports your native encoding
101 perl -Mencoding=latin2 -e '...' # Feeling centrally European?
102 perl -Mencoding=euc-ko -e '...'
104 # or from the shebang line
106 #!/your/path/to/perl -Mencoding="8859-6" # Arabian Nights
107 #!/your/path/to/perl -Mencoding=euc-tw
111 # A simple euc-cn => utf-8 converter
112 use encoding "euc-cn", STDOUT => "utf8"; while(<>){print};
114 # "no encoding;" supported (but not scoped!)
117 # an alternate way, Filter
118 use encoding "euc-jp", Filter=>1;
120 # now you can use kanji identifiers -- in euc-jp!
124 Let's start with a bit of history: Perl 5.6.0 introduced Unicode
125 support. You could apply C<substr()> and regexes even to complex CJK
126 characters -- so long as the script was written in UTF-8. But back
127 then text editors that supported UTF-8 were still rare and many users
128 rather chose to write scripts in legacy encodings, given up whole new
131 Rewind to the future: starting from perl 5.8.0 with B<encoding>
132 pragma, you can write your script in any encoding you like (so long
133 as the C<Encode> module supports it) and still enjoy Unicode support.
134 You can write a code in EUC-JP as follows:
136 my $Rakuda = "\xF1\xD1\xF1\xCC"; # Camel in Kanji
137 #<-char-><-char-> # 4 octets
138 s/\bCamel\b/$Rakuda/;
140 And with C<use encoding "euc-jp"> in effect, it is the same thing as
143 my $Rakuda = "\x{99F1}\x{99DD}"; # who Unicode Characters
144 s/\bCamel\b/$Rakuda/;
146 The B<encoding> pragma also modifies the filehandle disciplines of
147 STDIN, STDOUT, and STDERR to the specified encoding. Therefore,
149 use encoding "euc-jp";
150 my $message = "Camel is the symbol of perl.\n";
151 my $Rakuda = "\xF1\xD1\xF1\xCC"; # Camel in Kanji
152 $message =~ s/\bCamel\b/$Rakuda/;
155 Will print "\xF1\xD1\xF1\xCC is the symbol of perl.\n",
156 not "\x{99F1}\x{99DD} is the symbol of perl.\n".
158 You can override this by giving extra arguments, see below.
164 =item use encoding [I<ENCNAME>] ;
166 Sets the script encoding to I<ENCNAME> and filehandle disciplines of
167 STDIN, STDOUT are set to ":encoding(I<ENCNAME>)". Note STDERR will
170 If no encoding is specified, the environment variable L<PERL_ENCODING>
171 is consulted. If no encoding can be found, the error C<Unknown encoding
172 'I<ENCNAME>'> will be thrown.
174 Note that non-STD file handles remain unaffected. Use C<use open> or
175 C<binmode> to change disciplines of those.
177 =item use encoding I<ENCNAME> [ STDIN =E<gt> I<ENCNAME_IN> ...] ;
179 You can also individually set encodings of STDIN and STDOUT via
180 STDI<FH> =E<gt> I<ENCNAME_FH> form. In this case, you cannot omit the
181 first I<ENCNAME>. C<STDI<FH> =E<gt> undef> turns the IO transcoding
186 Unsets the script encoding and the disciplines of STDIN, STDOUT are
187 reset to ":raw" (the default unprocessed raw stream of bytes).
195 The pragma is a per script, not a per block lexical. Only the last
196 C<use encoding> or C<matters, and it affects B<the whole script>.
197 However, <no encoding> pragma is supported and C<use encoding> can
198 appear as many times as you want in a given script. The multiple use
199 of this pragma is discouraged.
201 =head2 DO NOT MIX MULTIPLE ENCODINGS
203 Notice that only literals (string or regular expression) having only
204 legacy code points are affected: if you mix data like this
208 the data is assumed to be in (Latin 1 and) Unicode, not in your native
209 encoding. In other words, this will match in "greek":
215 "\xDF\x{100}" =~ /\x{3af}\x{100}/
217 since the C<\xDF> (ISO 8859-7 GREEK SMALL LETTER IOTA WITH TONOS) on
218 the left will B<not> be upgraded to C<\x{3af}> (Unicode GREEK SMALL
219 LETTER IOTA WITH TONOS) because of the C<\x{100}> on the left. You
220 should not be mixing your legacy data and Unicode in the same string.
222 This pragma also affects encoding of the 0x80..0xFF code point range:
223 normally characters in that range are left as eight-bit bytes (unless
224 they are combined with characters with code points 0x100 or larger,
225 in which case all characters need to become UTF-8 encoded), but if
226 the C<encoding> pragma is present, even the 0x80..0xFF range always
229 After all, the best thing about this pragma is that you don't have to
230 resort to \x... just to spell your name in native a encoding. So feel
231 free to put your strings in your encoding in quotes and regexes.
233 =head1 Non-ASCII Identifiers and Filter option
235 The magic of C<use encoding> is not applied to the names of
236 identifiers. In order to make C<${"4eba"}++> ($human++, where human
237 is a single Han ideograph) work, you still need to write your script
238 in UTF-8 or use a source filter.
240 In other words, the same restriction as Jperl applies.
242 If you dare to experiment, however, you can try Filter option.
246 =item use encoding I<ENCNAME> Filter=E<gt>1;
248 This turns encoding pragma into source filter. While the default
249 approach just decodes interpolated literals (in qq() and qr()), this
250 will apply source filter to entire source code. In this case, STDIN
251 and STDOUT remain untouched.
255 What does this mean? Your source code behaves as if it is written in
256 UTF-8. So even if your editor only supports Shift_JIS, for example.
257 You can still try examples in Chapter 15 of C<Programming Perl, 3rd
258 Ed.> For instance, you can use UTF-8 identifiers.
260 This option is significantly slower and (as of this writing) non-ASCII
261 identifiers are not very stable WITHOUT this option and with the
262 source code written in UTF-8.
264 To make your script in legacy encoding work with minimum effort,
265 do not use Filter=E<gt>1.
267 =head1 EXAMPLE - Greekperl
269 use encoding "iso 8859-7";
271 # The \xDF of ISO 8859-7 (Greek) is \x{3af} in Unicode.
276 printf "%#x\n", ord($a); # will print 0x3af, not 0xdf
280 # $c will be "\x{3af}\x{100}", not "\x{df}\x{100}".
282 # chr() is affected, and ...
284 print "mega\n" if ord(chr(0xdf)) == 0x3af;
286 # ... ord() is affected by the encoding pragma ...
288 print "tera\n" if ord(pack("C", 0xdf)) == 0x3af;
290 # ... as are eq and cmp ...
292 print "peta\n" if "\x{3af}" eq pack("C", 0xdf);
293 print "exa\n" if "\x{3af}" cmp pack("C", 0xdf) == 0;
295 # ... but pack/unpack C are not affected, in case you still
296 # want back to your native encoding
298 print "zetta\n" if unpack("C", (pack("C", 0xdf))) == 0xdf;
300 =head1 KNOWN PROBLEMS
302 For native multibyte encodings (either fixed or variable length)
303 the current implementation of the regular expressions may introduce
304 recoding errors for longer regular expression literals than 127 bytes.
306 The encoding pragma is not supported on EBCDIC platforms.
311 L<perlunicode>, L<Encode>, L<open>, L<Filter::Util::Call>,
313 Ch. 15 of C<Programming Perl (3rd Edition)>
314 by Larry Wall, Tom Christiansen, Jon Orwant;
315 O'Reilly & Associates; ISBN 0-596-00027-8