2 our $VERSION = do { my @r = (q$Revision: 1.30 $ =~ /\d+/g); sprintf "%d."."%02d" x $#r, @r };
10 Carp::croak "encoding pragma does not support EBCDIC platforms";
14 our $HAS_PERLIO = exists $INC{"PerlIO/encoding.pm"};
15 $HAS_PERLIO or binmode(STDIN);
21 $name ||= $ENV{PERL_ENCODING};
23 my $enc = find_encoding($name);
24 unless (defined $enc) {
26 Carp::croak "Unknown encoding '$name'";
28 unless ($arg{Filter}){
29 ${^ENCODING} = $enc; # this is all you need, actually.
30 $HAS_PERLIO or return 1;
31 for my $h (qw(STDIN STDOUT)){
33 unless (defined find_encoding($arg{$h})) {
35 Carp::croak "Unknown encoding for $h, '$arg{$h}'";
37 eval qq{ binmode($h, ":encoding($arg{$h})") };
39 unless (exists $arg{$h}){
40 eval qq{ binmode($h, ":encoding($name)") };
49 defined(${^ENCODING}) and undef ${^ENCODING};
51 require Filter::Util::Call ;
52 Filter::Util::Call->import ;
57 if (($status = filter_read()) > 0){
58 $_ = $enc->decode($_, 1);
64 # warn "Filter installed";
66 return 1; # I doubt if we need it, though
74 if ($INC{"Filter/Util/Call.pm"}){
75 eval { filter_del() };
86 encoding - allows you to write your script in non-ascii or non-utf8
90 use encoding "greek"; # Perl like Greek to you?
91 use encoding "euc-jp"; # Jperl!
93 # or you can even do this if your shell supports your native encoding
95 perl -Mencoding=latin2 -e '...' # Feeling centrally European?
96 perl -Mencoding=euc-ko -e '...' # Korean
98 # or from the shebang line
100 #!/your/path/to/perl -Mencoding="8859-6" # Arabian Nights
101 #!/your/path/to/perl -Mencoding=euc-tw # Taiwanese
105 # A simple euc-cn => utf-8 converter
106 use encoding "euc-cn", STDOUT => "utf8"; while(<>){print}; # Chinese
108 # "no encoding;" supported (but not scoped!)
111 # an alternate way, Filter
112 use encoding "euc-jp", Filter=>1;
114 # now you can use kanji identifiers -- in euc-jp!
118 Let's start with a bit of history: Perl 5.6.0 introduced Unicode
119 support. You could apply C<substr()> and regexes even to complex CJK
120 characters -- so long as the script was written in UTF-8. But back
121 then text editors that supported UTF-8 were still rare and many users
122 rather chose to write scripts in legacy encodings, given up whole new
125 Rewind to the future: starting from perl 5.8.0 with B<encoding>
126 pragma, you can write your script in any encoding you like (so long
127 as the C<Encode> module supports it) and still enjoy Unicode support.
128 You can write a code in EUC-JP as follows:
130 my $Rakuda = "\xF1\xD1\xF1\xCC"; # Camel in Kanji
131 #<-char-><-char-> # 4 octets
132 s/\bCamel\b/$Rakuda/;
134 And with C<use encoding "euc-jp"> in effect, it is the same thing as
137 my $Rakuda = "\x{99F1}\x{99DD}"; # two Unicode Characters
138 s/\bCamel\b/$Rakuda/;
140 The B<encoding> pragma also modifies the filehandle disciplines of
141 STDIN, STDOUT, and STDERR to the specified encoding. Therefore,
143 use encoding "euc-jp";
144 my $message = "Camel is the symbol of perl.\n";
145 my $Rakuda = "\xF1\xD1\xF1\xCC"; # Camel in Kanji
146 $message =~ s/\bCamel\b/$Rakuda/;
149 Will print "\xF1\xD1\xF1\xCC is the symbol of perl.\n",
150 not "\x{99F1}\x{99DD} is the symbol of perl.\n".
152 You can override this by giving extra arguments, see below.
158 =item use encoding [I<ENCNAME>] ;
160 Sets the script encoding to I<ENCNAME> and filehandle disciplines of
161 STDIN, STDOUT are set to ":encoding(I<ENCNAME>)". Note STDERR will
164 If no encoding is specified, the environment variable L<PERL_ENCODING>
165 is consulted. If no encoding can be found, the error C<Unknown encoding
166 'I<ENCNAME>'> will be thrown.
168 Note that non-STD file handles remain unaffected. Use C<use open> or
169 C<binmode> to change disciplines of those.
171 =item use encoding I<ENCNAME> [ STDIN =E<gt> I<ENCNAME_IN> ...] ;
173 You can also individually set encodings of STDIN and STDOUT via
174 C<< STDIN => I<ENCNAME> >> form. In this case, you cannot omit the
175 first I<ENCNAME>. C<< STDIN => undef >> turns the IO transcoding
180 Unsets the script encoding and the disciplines of STDIN, STDOUT are
181 reset to ":raw" (the default unprocessed raw stream of bytes).
189 The pragma is a per script, not a per block lexical. Only the last
190 C<use encoding> or C<no encoding> matters, and it affects B<the whole script>.
191 However, <no encoding> pragma is supported and C<use encoding> can
192 appear as many times as you want in a given script. The multiple use
193 of this pragma is discouraged.
195 =head2 DO NOT MIX MULTIPLE ENCODINGS
197 Notice that only literals (string or regular expression) having only
198 legacy code points are affected: if you mix data like this
202 the data is assumed to be in (Latin 1 and) Unicode, not in your native
203 encoding. In other words, this will match in "greek":
209 "\xDF\x{100}" =~ /\x{3af}\x{100}/
211 since the C<\xDF> (ISO 8859-7 GREEK SMALL LETTER IOTA WITH TONOS) on
212 the left will B<not> be upgraded to C<\x{3af}> (Unicode GREEK SMALL
213 LETTER IOTA WITH TONOS) because of the C<\x{100}> on the left. You
214 should not be mixing your legacy data and Unicode in the same string.
216 This pragma also affects encoding of the 0x80..0xFF code point range:
217 normally characters in that range are left as eight-bit bytes (unless
218 they are combined with characters with code points 0x100 or larger,
219 in which case all characters need to become UTF-8 encoded), but if
220 the C<encoding> pragma is present, even the 0x80..0xFF range always
223 After all, the best thing about this pragma is that you don't have to
224 resort to \x... just to spell your name in native a encoding. So feel
225 free to put your strings in your encoding in quotes and regexes.
227 =head1 Non-ASCII Identifiers and Filter option
229 The magic of C<use encoding> is not applied to the names of
230 identifiers. In order to make C<${"\x{4eba}"}++> ($human++, where human
231 is a single Han ideograph) work, you still need to write your script
232 in UTF-8 or use a source filter.
234 In other words, the same restriction as Jperl applies.
236 If you dare to experiment, however, you can try Filter option.
240 =item use encoding I<ENCNAME> Filter=E<gt>1;
242 This turns encoding pragma into source filter. While the default
243 approach just decodes interpolated literals (in qq() and qr()), this
244 will apply source filter to entire source code. In this case, STDIN
245 and STDOUT remain untouched.
249 What does this mean? Your source code behaves as if it is written in
250 UTF-8. So even if your editor only supports Shift_JIS, for example.
251 You can still try examples in Chapter 15 of C<Programming Perl, 3rd
252 Ed.> For instance, you can use UTF-8 identifiers.
254 This option is significantly slower and (as of this writing) non-ASCII
255 identifiers are not very stable WITHOUT this option and with the
256 source code written in UTF-8.
258 To make your script in legacy encoding work with minimum effort,
259 do not use Filter=E<gt>1.
261 =head1 EXAMPLE - Greekperl
263 use encoding "iso 8859-7";
265 # The \xDF of ISO 8859-7 (Greek) is \x{3af} in Unicode.
270 printf "%#x\n", ord($a); # will print 0x3af, not 0xdf
274 # $c will be "\x{3af}\x{100}", not "\x{df}\x{100}".
276 # chr() is affected, and ...
278 print "mega\n" if ord(chr(0xdf)) == 0x3af;
280 # ... ord() is affected by the encoding pragma ...
282 print "tera\n" if ord(pack("C", 0xdf)) == 0x3af;
284 # ... as are eq and cmp ...
286 print "peta\n" if "\x{3af}" eq pack("C", 0xdf);
287 print "exa\n" if "\x{3af}" cmp pack("C", 0xdf) == 0;
289 # ... but pack/unpack C are not affected, in case you still
290 # want back to your native encoding
292 print "zetta\n" if unpack("C", (pack("C", 0xdf))) == 0xdf;
294 =head1 KNOWN PROBLEMS
296 For native multibyte encodings (either fixed or variable length)
297 the current implementation of the regular expressions may introduce
298 recoding errors for longer regular expression literals than 127 bytes.
300 The encoding pragma is not supported on EBCDIC platforms.
305 L<perlunicode>, L<Encode>, L<open>, L<Filter::Util::Call>,
307 Ch. 15 of C<Programming Perl (3rd Edition)>
308 by Larry Wall, Tom Christiansen, Jon Orwant;
309 O'Reilly & Associates; ISBN 0-596-00027-8