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1 | package encoding; |
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2 | our $VERSION = do { my @r = (q$Revision: 1.35 $ =~ /\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 | |
7 | BEGIN { |
8 | if (ord("A") == 193) { |
9 | require Carp; |
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10 | Carp::croak("encoding pragma does not support EBCDIC platforms"); |
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11 | } |
12 | } |
13 | |
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14 | our $HAS_PERLIO = 0; |
15 | eval { require PerlIO::encoding }; |
16 | unless ($@){ |
17 | $HAS_PERLIO = (PerlIO::encoding->VERSION >= 0.02); |
18 | } |
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19 | |
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20 | sub import { |
21 | my $class = shift; |
22 | my $name = shift; |
23 | my %arg = @_; |
24 | $name ||= $ENV{PERL_ENCODING}; |
25 | |
26 | my $enc = find_encoding($name); |
27 | unless (defined $enc) { |
28 | require Carp; |
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29 | Carp::croak("Unknown encoding '$name'"); |
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30 | } |
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31 | unless ($arg{Filter}){ |
32 | ${^ENCODING} = $enc; # this is all you need, actually. |
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33 | $HAS_PERLIO or return 1; |
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34 | for my $h (qw(STDIN STDOUT)){ |
35 | if ($arg{$h}){ |
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36 | unless (defined find_encoding($arg{$h})) { |
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37 | require Carp; |
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38 | Carp::croak("Unknown encoding for $h, '$arg{$h}'"); |
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39 | } |
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40 | eval { binmode($h, ":encoding($arg{$h})") }; |
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41 | }else{ |
42 | unless (exists $arg{$h}){ |
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43 | eval { |
44 | no warnings 'uninitialized'; |
45 | binmode($h, ":encoding($name)"); |
46 | }; |
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47 | } |
48 | } |
49 | if ($@){ |
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50 | require Carp; |
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51 | Carp::croak($@); |
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52 | } |
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53 | } |
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54 | }else{ |
55 | defined(${^ENCODING}) and undef ${^ENCODING}; |
56 | eval { |
57 | require Filter::Util::Call ; |
58 | Filter::Util::Call->import ; |
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59 | binmode(STDIN); |
60 | binmode(STDOUT); |
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61 | filter_add(sub{ |
62 | my $status; |
63 | if (($status = filter_read()) > 0){ |
64 | $_ = $enc->decode($_, 1); |
65 | # warn $_; |
66 | } |
67 | $status ; |
68 | }); |
69 | }; |
70 | # warn "Filter installed"; |
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71 | } |
72 | return 1; # I doubt if we need it, though |
73 | } |
74 | |
75 | sub unimport{ |
76 | no warnings; |
77 | undef ${^ENCODING}; |
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78 | if ($HAS_PERLIO){ |
79 | binmode(STDIN, ":raw"); |
80 | binmode(STDOUT, ":raw"); |
81 | }else{ |
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82 | binmode(STDIN); |
83 | binmode(STDOUT); |
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84 | } |
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85 | if ($INC{"Filter/Util/Call.pm"}){ |
86 | eval { filter_del() }; |
87 | } |
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88 | } |
89 | |
90 | 1; |
91 | __END__ |
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92 | |
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93 | =pod |
94 | |
95 | =head1 NAME |
96 | |
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97 | encoding - allows you to write your script in non-ascii or non-utf8 |
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98 | |
99 | =head1 SYNOPSIS |
100 | |
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101 | use encoding "greek"; # Perl like Greek to you? |
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102 | use encoding "euc-jp"; # Jperl! |
103 | |
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104 | # or you can even do this if your shell supports your native encoding |
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105 | |
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106 | perl -Mencoding=latin2 -e '...' # Feeling centrally European? |
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107 | perl -Mencoding=euc-kr -e '...' # Or Korean? |
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108 | |
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109 | # more control |
110 | |
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111 | # A simple euc-cn => utf-8 converter |
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112 | use encoding "euc-cn", STDOUT => "utf8"; while(<>){print}; |
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113 | |
114 | # "no encoding;" supported (but not scoped!) |
115 | no encoding; |
116 | |
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117 | # an alternate way, Filter |
118 | use encoding "euc-jp", Filter=>1; |
119 | use utf8; |
120 | # now you can use kanji identifiers -- in euc-jp! |
121 | |
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122 | =head1 ABSTRACT |
123 | |
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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 |
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127 | then, text editors that supported UTF-8 were still rare and many users |
128 | instead chose to write scripts in legacy encodings, giving up a whole |
129 | new feature of Perl 5.6. |
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130 | |
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131 | Rewind to the future: starting from perl 5.8.0 with the B<encoding> |
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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. |
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134 | You can write code in EUC-JP as follows: |
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135 | |
136 | my $Rakuda = "\xF1\xD1\xF1\xCC"; # Camel in Kanji |
137 | #<-char-><-char-> # 4 octets |
138 | s/\bCamel\b/$Rakuda/; |
139 | |
140 | And with C<use encoding "euc-jp"> in effect, it is the same thing as |
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141 | the code in UTF-8: |
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142 | |
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143 | my $Rakuda = "\x{99F1}\x{99DD}"; # two Unicode Characters |
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144 | s/\bCamel\b/$Rakuda/; |
145 | |
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146 | The B<encoding> pragma also modifies the filehandle disciplines of |
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147 | STDIN, STDOUT, and STDERR to the specified encoding. Therefore, |
148 | |
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/; |
153 | print $message; |
154 | |
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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". |
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157 | |
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158 | You can override this by giving extra arguments; see below. |
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159 | |
160 | =head1 USAGE |
161 | |
162 | =over 4 |
163 | |
164 | =item use encoding [I<ENCNAME>] ; |
165 | |
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166 | Sets the script encoding to I<ENCNAME>. Filehandle disciplines of |
167 | STDIN and STDOUT are set to ":encoding(I<ENCNAME>)". Note that STDERR |
168 | will not be changed. |
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169 | |
170 | If no encoding is specified, the environment variable L<PERL_ENCODING> |
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171 | is consulted. If no encoding can be found, the error C<Unknown encoding |
172 | 'I<ENCNAME>'> will be thrown. |
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173 | |
174 | Note that non-STD file handles remain unaffected. Use C<use open> or |
175 | C<binmode> to change disciplines of those. |
176 | |
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177 | =item use encoding I<ENCNAME> [ STDIN =E<gt> I<ENCNAME_IN> ...] ; |
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178 | |
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179 | You can also individually set encodings of STDIN and STDOUT via the |
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180 | C<< STDIN => I<ENCNAME> >> form. In this case, you cannot omit the |
181 | first I<ENCNAME>. C<< STDIN => undef >> turns the IO transcoding |
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182 | completely off. |
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183 | |
184 | =item no encoding; |
185 | |
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186 | Unsets the script encoding. The disciplines of STDIN, STDOUT are |
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187 | reset to ":raw" (the default unprocessed raw stream of bytes). |
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188 | |
189 | =back |
190 | |
191 | =head1 CAVEATS |
192 | |
193 | =head2 NOT SCOPED |
194 | |
195 | The pragma is a per script, not a per block lexical. Only the last |
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196 | C<use encoding> or C<no encoding> matters, and it affects |
197 | B<the whole script>. However, the <no encoding> pragma is supported and |
198 | B<use encoding> can appear as many times as you want in a given script. |
199 | The multiple use of this pragma is discouraged. |
200 | |
201 | Because of this nature, the use of this pragma inside the module is |
202 | strongly discouraged (because the influence of this pragma lasts not |
203 | only for the module but the script that uses). But if you have to, |
204 | make sure you say C<no encoding> at the end of the module so you |
205 | contain the influence of the pragma within the module. |
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206 | |
207 | =head2 DO NOT MIX MULTIPLE ENCODINGS |
208 | |
209 | Notice that only literals (string or regular expression) having only |
210 | legacy code points are affected: if you mix data like this |
211 | |
212 | \xDF\x{100} |
213 | |
214 | the data is assumed to be in (Latin 1 and) Unicode, not in your native |
215 | encoding. In other words, this will match in "greek": |
216 | |
217 | "\xDF" =~ /\x{3af}/ |
218 | |
219 | but this will not |
220 | |
221 | "\xDF\x{100}" =~ /\x{3af}\x{100}/ |
222 | |
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223 | since the C<\xDF> (ISO 8859-7 GREEK SMALL LETTER IOTA WITH TONOS) on |
224 | the left will B<not> be upgraded to C<\x{3af}> (Unicode GREEK SMALL |
225 | LETTER IOTA WITH TONOS) because of the C<\x{100}> on the left. You |
226 | should not be mixing your legacy data and Unicode in the same string. |
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227 | |
228 | This pragma also affects encoding of the 0x80..0xFF code point range: |
229 | normally characters in that range are left as eight-bit bytes (unless |
230 | they are combined with characters with code points 0x100 or larger, |
231 | in which case all characters need to become UTF-8 encoded), but if |
232 | the C<encoding> pragma is present, even the 0x80..0xFF range always |
233 | gets UTF-8 encoded. |
234 | |
235 | After all, the best thing about this pragma is that you don't have to |
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236 | resort to \x{....} just to spell your name in a native encoding. |
237 | So feel free to put your strings in your encoding in quotes and |
238 | regexes. |
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239 | |
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240 | =head1 Non-ASCII Identifiers and Filter option |
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241 | |
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242 | The magic of C<use encoding> is not applied to the names of |
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243 | identifiers. In order to make C<${"\x{4eba}"}++> ($human++, where human |
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244 | is a single Han ideograph) work, you still need to write your script |
245 | in UTF-8 or use a source filter. |
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246 | |
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247 | In other words, the same restriction as with Jperl applies. |
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248 | |
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249 | If you dare to experiment, however, you can try the Filter option. |
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250 | |
251 | =over 4 |
252 | |
253 | =item use encoding I<ENCNAME> Filter=E<gt>1; |
254 | |
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255 | This turns the encoding pragma into a source filter. While the default |
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256 | approach just decodes interpolated literals (in qq() and qr()), this |
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257 | will apply a source filter to the entire source code. In this case, |
258 | STDIN and STDOUT remain untouched. |
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259 | |
260 | =back |
261 | |
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262 | What does this mean? Your source code behaves as if it is written in |
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263 | UTF-8. So even if your editor only supports Shift_JIS, for example, |
264 | you can still try examples in Chapter 15 of C<Programming Perl, 3rd |
265 | Ed.>. For instance, you can use UTF-8 identifiers. |
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266 | |
267 | This option is significantly slower and (as of this writing) non-ASCII |
268 | identifiers are not very stable WITHOUT this option and with the |
269 | source code written in UTF-8. |
270 | |
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271 | To make your script in legacy encoding work with minimum effort, |
272 | do not use Filter=E<gt>1. |
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273 | |
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274 | =head1 EXAMPLE - Greekperl |
275 | |
276 | use encoding "iso 8859-7"; |
277 | |
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278 | # \xDF in ISO 8859-7 (Greek) is \x{3af} in Unicode. |
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279 | |
280 | $a = "\xDF"; |
281 | $b = "\x{100}"; |
282 | |
283 | printf "%#x\n", ord($a); # will print 0x3af, not 0xdf |
284 | |
285 | $c = $a . $b; |
286 | |
287 | # $c will be "\x{3af}\x{100}", not "\x{df}\x{100}". |
288 | |
289 | # chr() is affected, and ... |
290 | |
291 | print "mega\n" if ord(chr(0xdf)) == 0x3af; |
292 | |
293 | # ... ord() is affected by the encoding pragma ... |
294 | |
295 | print "tera\n" if ord(pack("C", 0xdf)) == 0x3af; |
296 | |
297 | # ... as are eq and cmp ... |
298 | |
299 | print "peta\n" if "\x{3af}" eq pack("C", 0xdf); |
300 | print "exa\n" if "\x{3af}" cmp pack("C", 0xdf) == 0; |
301 | |
302 | # ... but pack/unpack C are not affected, in case you still |
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303 | # want to go back to your native encoding |
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304 | |
305 | print "zetta\n" if unpack("C", (pack("C", 0xdf))) == 0xdf; |
306 | |
307 | =head1 KNOWN PROBLEMS |
308 | |
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309 | For native multibyte encodings (either fixed or variable length), |
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310 | the current implementation of the regular expressions may introduce |
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311 | recoding errors for regular expression literals longer than 127 bytes. |
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312 | |
313 | The encoding pragma is not supported on EBCDIC platforms. |
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314 | (Porters who are willing and able to remove this limitation are |
315 | welcome.) |
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316 | |
317 | =head1 SEE ALSO |
318 | |
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319 | L<perlunicode>, L<Encode>, L<open>, L<Filter::Util::Call>, |
320 | |
321 | Ch. 15 of C<Programming Perl (3rd Edition)> |
322 | by Larry Wall, Tom Christiansen, Jon Orwant; |
323 | O'Reilly & Associates; ISBN 0-596-00027-8 |
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324 | |
325 | =cut |