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1 | package encoding; |
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2 | our $VERSION = do { my @r = (q$Revision: 1.42 $ =~ /\d+/g); sprintf "%d."."%02d" x $#r, @r }; |
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3 | |
4 | use Encode; |
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5 | use strict; |
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6 | our $DEBUG = 0; |
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7 | |
8 | BEGIN { |
9 | if (ord("A") == 193) { |
10 | require Carp; |
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11 | Carp::croak("encoding pragma does not support EBCDIC platforms"); |
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12 | } |
13 | } |
14 | |
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15 | our $HAS_PERLIO = 0; |
16 | eval { require PerlIO::encoding }; |
17 | unless ($@){ |
18 | $HAS_PERLIO = (PerlIO::encoding->VERSION >= 0.02); |
19 | } |
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20 | |
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21 | sub _exception{ |
22 | my $name = shift; |
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 |
30 | } |
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31 | |
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32 | sub import { |
33 | my $class = shift; |
34 | my $name = shift; |
35 | my %arg = @_; |
36 | $name ||= $ENV{PERL_ENCODING}; |
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37 | my $enc = find_encoding($name); |
38 | unless (defined $enc) { |
39 | require Carp; |
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40 | Carp::croak("Unknown encoding '$name'"); |
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41 | } |
fa6f41cf |
42 | $name = $enc->name; # canonize |
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43 | unless ($arg{Filter}) { |
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44 | $DEBUG and warn "_exception($name) = ", _exception($name); |
45 | _exception($name) or ${^ENCODING} = $enc; |
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46 | $HAS_PERLIO or return 1; |
aae85ceb |
47 | }else{ |
48 | defined(${^ENCODING}) and undef ${^ENCODING}; |
151b5d36 |
49 | # implicitly 'use utf8' |
50 | require utf8; # to fetch $utf8::hint_bits; |
51 | $^H |= $utf8::hint_bits; |
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52 | eval { |
53 | require Filter::Util::Call ; |
54 | Filter::Util::Call->import ; |
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55 | filter_add(sub{ |
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56 | my $status = filter_read(); |
57 | if ($status > 0){ |
58 | # $DEBUG and warn $_; |
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59 | $_ = $enc->decode($_, 1); |
151b5d36 |
60 | $DEBUG and warn $_; |
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61 | } |
62 | $status ; |
63 | }); |
64 | }; |
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65 | } $DEBUG and warn "Filter installed"; |
151b5d36 |
66 | for my $h (qw(STDIN STDOUT)){ |
67 | if ($arg{$h}){ |
68 | unless (defined find_encoding($arg{$h})) { |
69 | require Carp; |
70 | Carp::croak("Unknown encoding for $h, '$arg{$h}'"); |
71 | } |
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72 | eval { binmode($h, ":raw :encoding($arg{$h})") }; |
151b5d36 |
73 | }else{ |
74 | unless (exists $arg{$h}){ |
75 | eval { |
76 | no warnings 'uninitialized'; |
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77 | binmode($h, ":raw :encoding($name)"); |
151b5d36 |
78 | }; |
79 | } |
80 | } |
81 | if ($@){ |
82 | require Carp; |
83 | Carp::croak($@); |
84 | } |
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85 | } |
86 | return 1; # I doubt if we need it, though |
87 | } |
88 | |
89 | sub unimport{ |
90 | no warnings; |
91 | undef ${^ENCODING}; |
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92 | if ($HAS_PERLIO){ |
93 | binmode(STDIN, ":raw"); |
94 | binmode(STDOUT, ":raw"); |
95 | }else{ |
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96 | binmode(STDIN); |
97 | binmode(STDOUT); |
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98 | } |
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99 | if ($INC{"Filter/Util/Call.pm"}){ |
100 | eval { filter_del() }; |
101 | } |
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102 | } |
103 | |
104 | 1; |
105 | __END__ |
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106 | |
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107 | =pod |
108 | |
109 | =head1 NAME |
110 | |
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111 | encoding - allows you to write your script in non-ascii or non-utf8 |
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112 | |
113 | =head1 SYNOPSIS |
114 | |
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115 | use encoding "greek"; # Perl like Greek to you? |
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116 | use encoding "euc-jp"; # Jperl! |
117 | |
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118 | # or you can even do this if your shell supports your native encoding |
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119 | |
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120 | perl -Mencoding=latin2 -e '...' # Feeling centrally European? |
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121 | perl -Mencoding=euc-kr -e '...' # Or Korean? |
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122 | |
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123 | # more control |
124 | |
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125 | # A simple euc-cn => utf-8 converter |
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126 | use encoding "euc-cn", STDOUT => "utf8"; while(<>){print}; |
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127 | |
128 | # "no encoding;" supported (but not scoped!) |
129 | no encoding; |
130 | |
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131 | # an alternate way, Filter |
132 | use encoding "euc-jp", Filter=>1; |
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133 | # now you can use kanji identifiers -- in euc-jp! |
134 | |
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135 | =head1 ABSTRACT |
136 | |
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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 |
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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. |
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143 | |
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144 | Rewind to the future: starting from perl 5.8.0 with the B<encoding> |
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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. |
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147 | You can write code in EUC-JP as follows: |
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148 | |
149 | my $Rakuda = "\xF1\xD1\xF1\xCC"; # Camel in Kanji |
150 | #<-char-><-char-> # 4 octets |
151 | s/\bCamel\b/$Rakuda/; |
152 | |
153 | And with C<use encoding "euc-jp"> in effect, it is the same thing as |
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154 | the code in UTF-8: |
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155 | |
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156 | my $Rakuda = "\x{99F1}\x{99DD}"; # two Unicode Characters |
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157 | s/\bCamel\b/$Rakuda/; |
158 | |
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159 | The B<encoding> pragma also modifies the filehandle disciplines of |
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160 | STDIN and STDOUT to the specified encoding. Therefore, |
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161 | |
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/; |
166 | print $message; |
167 | |
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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". |
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170 | |
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171 | You can override this by giving extra arguments; see below. |
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172 | |
173 | =head1 USAGE |
174 | |
175 | =over 4 |
176 | |
177 | =item use encoding [I<ENCNAME>] ; |
178 | |
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179 | Sets the script encoding to I<ENCNAME>. Filehandle disciplines of |
180 | STDIN and STDOUT are set to ":encoding(I<ENCNAME>)". Note that STDERR |
181 | will not be changed. |
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182 | |
183 | If no encoding is specified, the environment variable L<PERL_ENCODING> |
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184 | is consulted. If no encoding can be found, the error C<Unknown encoding |
185 | 'I<ENCNAME>'> will be thrown. |
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186 | |
187 | Note that non-STD file handles remain unaffected. Use C<use open> or |
188 | C<binmode> to change disciplines of those. |
189 | |
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190 | =item use encoding I<ENCNAME> [ STDIN =E<gt> I<ENCNAME_IN> ...] ; |
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191 | |
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192 | You can also individually set encodings of STDIN and STDOUT via the |
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193 | C<< STDIN => I<ENCNAME> >> form. In this case, you cannot omit the |
194 | first I<ENCNAME>. C<< STDIN => undef >> turns the IO transcoding |
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195 | completely off. |
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196 | |
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197 | =item use encoding I<ENCNAME> Filter=E<gt>1; |
198 | |
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 |
203 | |
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204 | =item no encoding; |
205 | |
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206 | Unsets the script encoding. The disciplines of STDIN, STDOUT are |
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207 | reset to ":raw" (the default unprocessed raw stream of bytes). |
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208 | |
209 | =back |
210 | |
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211 | =head1 The Filter Option |
212 | |
213 | The magic of C<use encoding> is not applied to the names of |
214 | identifiers. In order to make C<${"\x{4eba}"}++> ($human++, where human |
215 | is a single Han ideograph) work, you still need to write your script |
216 | in UTF-8 -- or use a source filter. That's what 'Filter=>1' does. |
217 | |
218 | |
219 | What does this mean? Your source code behaves as if it is written in |
220 | UTF-8 with 'use utf8' in effect. So even if your editor only supports |
221 | Shift_JIS, for example, you can still try examples in Chapter 15 of |
222 | C<Programming Perl, 3rd Ed.>. For instance, you can use UTF-8 |
223 | identifiers. |
224 | |
225 | This option is significantly slower and (as of this writing) non-ASCII |
226 | identifiers are not very stable WITHOUT this option and with the |
227 | source code written in UTF-8. |
228 | |
229 | =head2 Filter-related changes at Encode version 1.87 |
230 | |
231 | =over |
232 | |
233 | =item * |
234 | |
235 | The Filter option now sets STDIN and STDOUT like non-filter options. |
236 | And C<< STDIN=>I<ENCODING> >> and C<< STDOUT=>I<ENCODING> >> work like |
237 | non-filter version. |
238 | |
239 | =item * |
240 | |
241 | C<use utf8> is implicitly declared so you no longer have to C<use |
242 | utf8> to C<${"\x{4eba}"}++>. |
243 | |
244 | =back |
245 | |
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246 | =head1 CAVEATS |
247 | |
248 | =head2 NOT SCOPED |
249 | |
250 | The pragma is a per script, not a per block lexical. Only the last |
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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. |
255 | |
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. |
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261 | |
262 | =head2 DO NOT MIX MULTIPLE ENCODINGS |
263 | |
264 | Notice that only literals (string or regular expression) having only |
265 | legacy code points are affected: if you mix data like this |
266 | |
267 | \xDF\x{100} |
268 | |
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": |
271 | |
272 | "\xDF" =~ /\x{3af}/ |
273 | |
274 | but this will not |
275 | |
276 | "\xDF\x{100}" =~ /\x{3af}\x{100}/ |
277 | |
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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. |
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282 | |
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 |
288 | gets UTF-8 encoded. |
289 | |
290 | After all, the best thing about this pragma is that you don't have to |
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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 |
293 | regexes. |
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294 | |
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295 | =head2 format doesn't work well |
296 | |
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. |
301 | |
302 | # Save this one in utf8 |
303 | # replace *non-ascii* with a non-ascii string |
304 | my $camel; |
305 | format STDOUT = |
306 | *non-ascii*@>>>>>>> |
307 | $camel |
308 | . |
309 | $camel = "*non-ascii*"; |
310 | binmode(STDOUT=>':encoding(utf8)'); # bang! |
311 | write; # funny |
312 | print $camel, "\n"; # fine |
313 | |
314 | Without binmode this happens to work but without binmode, print() |
315 | fails instead of write(). |
316 | |
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 |
320 | Arabic and Hebrew). |
321 | |
322 | =head2 tr/// with ranges |
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323 | |
324 | The B<encoding> pragma works by decoding string literals in |
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325 | C<q//,qq//,qr//,qw///, qx//> and so forth. In perl 5.8.0, this |
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326 | does not apply to C<tr///>. Therefore, |
327 | |
328 | use encoding 'euc-jp'; |
329 | #.... |
330 | $kana =~ tr/\xA4\xA1-\xA4\xF3/\xA5\xA1-\xA5\xF3/; |
331 | # -------- -------- -------- -------- |
332 | |
333 | Does not work as |
334 | |
335 | $kana =~ tr/\x{3041}-\x{3093}/\x{30a1}-\x{30f3}/; |
336 | |
337 | =over |
338 | |
339 | =item Legend of characters above |
340 | |
341 | utf8 euc-jp charnames::viacode() |
342 | ----------------------------------------- |
343 | \x{3041} \xA4\xA1 HIRAGANA LETTER SMALL A |
344 | \x{3093} \xA4\xF3 HIRAGANA LETTER N |
345 | \x{30a1} \xA5\xA1 KATAKANA LETTER SMALL A |
346 | \x{30f3} \xA5\xF3 KATAKANA LETTER N |
347 | |
348 | =back |
349 | |
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350 | This counterintuitive behavior has been fixed in perl 5.8.1 and up |
351 | by INABA Hirohito. |
352 | |
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353 | =head3 workaround to tr///; |
354 | |
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355 | In perl 5.8.0, you can work aroud as follows; |
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356 | |
357 | use encoding 'euc-jp'; |
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358 | # .... |
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359 | eval qq{ \$kana =~ tr/\xA4\xA1-\xA4\xF3/\xA5\xA1-\xA5\xF3/ }; |
360 | |
361 | Note the C<tr//> expression is surronded by C<qq{}>. The idea behind |
362 | is the same as classic idiom that makes C<tr///> 'interpolate'. |
363 | |
364 | tr/$from/$to/; # wrong! |
365 | eval qq{ tr/$from/$to/ }; # workaround. |
366 | |
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 |
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369 | Porters so it has been fixed. |
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370 | |
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371 | =head1 EXAMPLE - Greekperl |
372 | |
373 | use encoding "iso 8859-7"; |
374 | |
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375 | # \xDF in ISO 8859-7 (Greek) is \x{3af} in Unicode. |
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376 | |
377 | $a = "\xDF"; |
378 | $b = "\x{100}"; |
379 | |
380 | printf "%#x\n", ord($a); # will print 0x3af, not 0xdf |
381 | |
382 | $c = $a . $b; |
383 | |
384 | # $c will be "\x{3af}\x{100}", not "\x{df}\x{100}". |
385 | |
386 | # chr() is affected, and ... |
387 | |
388 | print "mega\n" if ord(chr(0xdf)) == 0x3af; |
389 | |
390 | # ... ord() is affected by the encoding pragma ... |
391 | |
392 | print "tera\n" if ord(pack("C", 0xdf)) == 0x3af; |
393 | |
394 | # ... as are eq and cmp ... |
395 | |
396 | print "peta\n" if "\x{3af}" eq pack("C", 0xdf); |
397 | print "exa\n" if "\x{3af}" cmp pack("C", 0xdf) == 0; |
398 | |
399 | # ... but pack/unpack C are not affected, in case you still |
0ab8f81e |
400 | # want to go back to your native encoding |
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401 | |
402 | print "zetta\n" if unpack("C", (pack("C", 0xdf))) == 0xdf; |
403 | |
404 | =head1 KNOWN PROBLEMS |
405 | |
151b5d36 |
406 | =over |
407 | |
408 | =item * |
409 | |
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410 | For native multibyte encodings (either fixed or variable length), |
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411 | the current implementation of the regular expressions may introduce |
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412 | recoding errors for regular expression literals longer than 127 bytes. |
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413 | |
151b5d36 |
414 | =item * |
415 | |
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416 | The encoding pragma is not supported on EBCDIC platforms. |
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417 | (Porters who are willing and able to remove this limitation are |
418 | welcome.) |
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419 | |
151b5d36 |
420 | =back |
421 | |
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422 | =head1 SEE ALSO |
423 | |
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424 | L<perlunicode>, L<Encode>, L<open>, L<Filter::Util::Call>, |
425 | |
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 |
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429 | |
430 | =cut |