2 our $VERSION = do { my @r = (q$Revision: 1.41 $ =~ /\d+/g); sprintf "%d."."%02d" x $#r, @r };
11 Carp::croak("encoding pragma does not support EBCDIC platforms");
16 eval { require PerlIO::encoding };
18 $HAS_PERLIO = (PerlIO::encoding->VERSION >= 0.02);
23 $] > 5.008 and return 0; # 5.8.1 then no
24 my %utfs = map {$_=>1}
25 qw(utf8 UCS-2BE UCS-2LE UTF-16 UTF-16BE UTF-16LE
26 UTF-32 UTF-32BE UTF-32LE);
27 $utfs{$name} or return 0; # UTFs or no
28 require Config; Config->import(); our %Config;
29 return $Config{perl_patchlevel} == 0 # maintperl then no
36 $name ||= $ENV{PERL_ENCODING};
37 my $enc = find_encoding($name);
38 unless (defined $enc) {
40 Carp::croak("Unknown encoding '$name'");
42 $name = $enc->name; # canonize
43 unless ($arg{Filter}) {
44 $DEBUG and warn "_exception($name) = ", _exception($name);
45 _exception($name) or ${^ENCODING} = $enc;
46 $HAS_PERLIO or return 1;
48 defined(${^ENCODING}) and undef ${^ENCODING};
49 # implicitly 'use utf8'
50 require utf8; # to fetch $utf8::hint_bits;
51 $^H |= $utf8::hint_bits;
53 require Filter::Util::Call ;
54 Filter::Util::Call->import ;
56 my $status = filter_read();
59 $_ = $enc->decode($_, 1);
65 } $DEBUG and warn "Filter installed";
66 for my $h (qw(STDIN STDOUT)){
68 unless (defined find_encoding($arg{$h})) {
70 Carp::croak("Unknown encoding for $h, '$arg{$h}'");
72 eval { binmode($h, ":encoding($arg{$h})") };
74 unless (exists $arg{$h}){
76 no warnings 'uninitialized';
77 binmode($h, ":encoding($name)");
86 return 1; # I doubt if we need it, though
93 binmode(STDIN, ":raw");
94 binmode(STDOUT, ":raw");
99 if ($INC{"Filter/Util/Call.pm"}){
100 eval { filter_del() };
111 encoding - allows you to write your script in non-ascii or non-utf8
115 use encoding "greek"; # Perl like Greek to you?
116 use encoding "euc-jp"; # Jperl!
118 # or you can even do this if your shell supports your native encoding
120 perl -Mencoding=latin2 -e '...' # Feeling centrally European?
121 perl -Mencoding=euc-kr -e '...' # Or Korean?
125 # A simple euc-cn => utf-8 converter
126 use encoding "euc-cn", STDOUT => "utf8"; while(<>){print};
128 # "no encoding;" supported (but not scoped!)
131 # an alternate way, Filter
132 use encoding "euc-jp", Filter=>1;
133 # now you can use kanji identifiers -- in euc-jp!
137 Let's start with a bit of history: Perl 5.6.0 introduced Unicode
138 support. You could apply C<substr()> and regexes even to complex CJK
139 characters -- so long as the script was written in UTF-8. But back
140 then, text editors that supported UTF-8 were still rare and many users
141 instead chose to write scripts in legacy encodings, giving up a whole
142 new feature of Perl 5.6.
144 Rewind to the future: starting from perl 5.8.0 with the B<encoding>
145 pragma, you can write your script in any encoding you like (so long
146 as the C<Encode> module supports it) and still enjoy Unicode support.
147 You can write code in EUC-JP as follows:
149 my $Rakuda = "\xF1\xD1\xF1\xCC"; # Camel in Kanji
150 #<-char-><-char-> # 4 octets
151 s/\bCamel\b/$Rakuda/;
153 And with C<use encoding "euc-jp"> in effect, it is the same thing as
156 my $Rakuda = "\x{99F1}\x{99DD}"; # two Unicode Characters
157 s/\bCamel\b/$Rakuda/;
159 The B<encoding> pragma also modifies the filehandle disciplines of
160 STDIN and STDOUT to the specified encoding. Therefore,
162 use encoding "euc-jp";
163 my $message = "Camel is the symbol of perl.\n";
164 my $Rakuda = "\xF1\xD1\xF1\xCC"; # Camel in Kanji
165 $message =~ s/\bCamel\b/$Rakuda/;
168 Will print "\xF1\xD1\xF1\xCC is the symbol of perl.\n",
169 not "\x{99F1}\x{99DD} is the symbol of perl.\n".
171 You can override this by giving extra arguments; see below.
177 =item use encoding [I<ENCNAME>] ;
179 Sets the script encoding to I<ENCNAME>. Filehandle disciplines of
180 STDIN and STDOUT are set to ":encoding(I<ENCNAME>)". Note that STDERR
183 If no encoding is specified, the environment variable L<PERL_ENCODING>
184 is consulted. If no encoding can be found, the error C<Unknown encoding
185 'I<ENCNAME>'> will be thrown.
187 Note that non-STD file handles remain unaffected. Use C<use open> or
188 C<binmode> to change disciplines of those.
190 =item use encoding I<ENCNAME> [ STDIN =E<gt> I<ENCNAME_IN> ...] ;
192 You can also individually set encodings of STDIN and STDOUT via the
193 C<< STDIN => I<ENCNAME> >> form. In this case, you cannot omit the
194 first I<ENCNAME>. C<< STDIN => undef >> turns the IO transcoding
197 =item use encoding I<ENCNAME> Filter=E<gt>1;
199 This turns the encoding pragma into a source filter. While the
200 default approach just decodes interpolated literals (in qq() and
201 qr()), this will apply a source filter to the entire source code. See
202 L</"The Filter Option"> below for details
206 Unsets the script encoding. The disciplines of STDIN, STDOUT are
207 reset to ":raw" (the default unprocessed raw stream of bytes).
211 =head1 The Filter Option
213 The magic of C<use encoding> is not applied to the names of
214 identifiers. In order to make C<${"\x{4eba}"}++> ($human++, where human
215 is a single Han ideograph) work, you still need to write your script
216 in UTF-8 -- or use a source filter. That's what 'Filter=>1' does.
219 What does this mean? Your source code behaves as if it is written in
220 UTF-8 with 'use utf8' in effect. So even if your editor only supports
221 Shift_JIS, for example, you can still try examples in Chapter 15 of
222 C<Programming Perl, 3rd Ed.>. For instance, you can use UTF-8
225 This option is significantly slower and (as of this writing) non-ASCII
226 identifiers are not very stable WITHOUT this option and with the
227 source code written in UTF-8.
229 =head2 Filter-related changes at Encode version 1.87
235 The Filter option now sets STDIN and STDOUT like non-filter options.
236 And C<< STDIN=>I<ENCODING> >> and C<< STDOUT=>I<ENCODING> >> work like
241 C<use utf8> is implicitly declared so you no longer have to C<use
242 utf8> to C<${"\x{4eba}"}++>.
250 The pragma is a per script, not a per block lexical. Only the last
251 C<use encoding> or C<no encoding> matters, and it affects
252 B<the whole script>. However, the <no encoding> pragma is supported and
253 B<use encoding> can appear as many times as you want in a given script.
254 The multiple use of this pragma is discouraged.
256 Because of this nature, the use of this pragma inside the module is
257 strongly discouraged (because the influence of this pragma lasts not
258 only for the module but the script that uses). But if you have to,
259 make sure you say C<no encoding> at the end of the module so you
260 contain the influence of the pragma within the module.
262 =head2 DO NOT MIX MULTIPLE ENCODINGS
264 Notice that only literals (string or regular expression) having only
265 legacy code points are affected: if you mix data like this
269 the data is assumed to be in (Latin 1 and) Unicode, not in your native
270 encoding. In other words, this will match in "greek":
276 "\xDF\x{100}" =~ /\x{3af}\x{100}/
278 since the C<\xDF> (ISO 8859-7 GREEK SMALL LETTER IOTA WITH TONOS) on
279 the left will B<not> be upgraded to C<\x{3af}> (Unicode GREEK SMALL
280 LETTER IOTA WITH TONOS) because of the C<\x{100}> on the left. You
281 should not be mixing your legacy data and Unicode in the same string.
283 This pragma also affects encoding of the 0x80..0xFF code point range:
284 normally characters in that range are left as eight-bit bytes (unless
285 they are combined with characters with code points 0x100 or larger,
286 in which case all characters need to become UTF-8 encoded), but if
287 the C<encoding> pragma is present, even the 0x80..0xFF range always
290 After all, the best thing about this pragma is that you don't have to
291 resort to \x{....} just to spell your name in a native encoding.
292 So feel free to put your strings in your encoding in quotes and
295 =head2 format doesn't work well
297 This pragma doesn't work well with format because PerlIO does not
298 get along very well with it. When format contains non-ascii
299 characters it prints funny or gets "wide character warnings".
300 To understand it, try the code below.
302 # Save this one in utf8
303 # replace *non-ascii* with a non-ascii string
309 $camel = "*non-ascii*";
310 binmode(STDOUT=>':encoding(utf8)'); # bang!
312 print $camel, "\n"; # fine
314 Without binmode this happens to work but without binmode, print()
315 fails instead of write().
317 At any rate, the very use of format is questionable when it comes to
318 unicode characters since you have to consider such things as character
319 width (i.e. double-width for ideographs) and directions (i.e. BIDI for
322 =head2 tr/// with ranges
324 The B<encoding> pragma works by decoding string literals in
325 C<q//,qq//,qr//,qw///, qx//> and so forth. In perl 5.8.0, this
326 does not apply to C<tr///>. Therefore,
328 use encoding 'euc-jp';
330 $kana =~ tr/\xA4\xA1-\xA4\xF3/\xA5\xA1-\xA5\xF3/;
331 # -------- -------- -------- --------
335 $kana =~ tr/\x{3041}-\x{3093}/\x{30a1}-\x{30f3}/;
339 =item Legend of characters above
341 utf8 euc-jp charnames::viacode()
342 -----------------------------------------
343 \x{3041} \xA4\xA1 HIRAGANA LETTER SMALL A
344 \x{3093} \xA4\xF3 HIRAGANA LETTER N
345 \x{30a1} \xA5\xA1 KATAKANA LETTER SMALL A
346 \x{30f3} \xA5\xF3 KATAKANA LETTER N
350 This counterintuitive behavior has been fixed in perl 5.8.1 and up
353 =head3 workaround to tr///;
355 In perl 5.8.0, you can work aroud as follows;
357 use encoding 'euc-jp';
359 eval qq{ \$kana =~ tr/\xA4\xA1-\xA4\xF3/\xA5\xA1-\xA5\xF3/ };
361 Note the C<tr//> expression is surronded by C<qq{}>. The idea behind
362 is the same as classic idiom that makes C<tr///> 'interpolate'.
364 tr/$from/$to/; # wrong!
365 eval qq{ tr/$from/$to/ }; # workaround.
367 Nevertheless, in case of B<encoding> pragma even C<q//> is affected so
368 C<tr///> not being decoded was obviously against the will of Perl5
369 Porters so it has been fixed.
371 =head1 EXAMPLE - Greekperl
373 use encoding "iso 8859-7";
375 # \xDF in ISO 8859-7 (Greek) is \x{3af} in Unicode.
380 printf "%#x\n", ord($a); # will print 0x3af, not 0xdf
384 # $c will be "\x{3af}\x{100}", not "\x{df}\x{100}".
386 # chr() is affected, and ...
388 print "mega\n" if ord(chr(0xdf)) == 0x3af;
390 # ... ord() is affected by the encoding pragma ...
392 print "tera\n" if ord(pack("C", 0xdf)) == 0x3af;
394 # ... as are eq and cmp ...
396 print "peta\n" if "\x{3af}" eq pack("C", 0xdf);
397 print "exa\n" if "\x{3af}" cmp pack("C", 0xdf) == 0;
399 # ... but pack/unpack C are not affected, in case you still
400 # want to go back to your native encoding
402 print "zetta\n" if unpack("C", (pack("C", 0xdf))) == 0xdf;
404 =head1 KNOWN PROBLEMS
410 For native multibyte encodings (either fixed or variable length),
411 the current implementation of the regular expressions may introduce
412 recoding errors for regular expression literals longer than 127 bytes.
416 The encoding pragma is not supported on EBCDIC platforms.
417 (Porters who are willing and able to remove this limitation are
424 L<perlunicode>, L<Encode>, L<open>, L<Filter::Util::Call>,
426 Ch. 15 of C<Programming Perl (3rd Edition)>
427 by Larry Wall, Tom Christiansen, Jon Orwant;
428 O'Reilly & Associates; ISBN 0-596-00027-8