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2 | # Time-stamp: "2004-01-11 18:35:34 AST" |
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3 | |
4 | =head1 NAME |
5 | |
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6 | Locale::Maketext - framework for localization |
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7 | |
8 | =head1 SYNOPSIS |
9 | |
10 | package MyProgram; |
11 | use strict; |
12 | use MyProgram::L10N; |
13 | # ...which inherits from Locale::Maketext |
14 | my $lh = MyProgram::L10N->get_handle() || die "What language?"; |
15 | ... |
16 | # And then any messages your program emits, like: |
17 | warn $lh->maketext( "Can't open file [_1]: [_2]\n", $f, $! ); |
18 | ... |
19 | |
20 | =head1 DESCRIPTION |
21 | |
22 | It is a common feature of applications (whether run directly, |
23 | or via the Web) for them to be "localized" -- i.e., for them |
24 | to a present an English interface to an English-speaker, a German |
25 | interface to a German-speaker, and so on for all languages it's |
26 | programmed with. Locale::Maketext |
27 | is a framework for software localization; it provides you with the |
28 | tools for organizing and accessing the bits of text and text-processing |
29 | code that you need for producing localized applications. |
30 | |
31 | In order to make sense of Maketext and how all its |
32 | components fit together, you should probably |
33 | go read L<Locale::Maketext::TPJ13|Locale::Maketext::TPJ13>, and |
34 | I<then> read the following documentation. |
35 | |
36 | You may also want to read over the source for C<File::Findgrep> |
37 | and its constituent modules -- they are a complete (if small) |
38 | example application that uses Maketext. |
39 | |
40 | =head1 QUICK OVERVIEW |
41 | |
42 | The basic design of Locale::Maketext is object-oriented, and |
43 | Locale::Maketext is an abstract base class, from which you |
44 | derive a "project class". |
45 | The project class (with a name like "TkBocciBall::Localize", |
46 | which you then use in your module) is in turn the base class |
47 | for all the "language classes" for your project |
48 | (with names "TkBocciBall::Localize::it", |
49 | "TkBocciBall::Localize::en", |
50 | "TkBocciBall::Localize::fr", etc.). |
51 | |
52 | A language class is |
53 | a class containing a lexicon of phrases as class data, |
54 | and possibly also some methods that are of use in interpreting |
55 | phrases in the lexicon, or otherwise dealing with text in that |
56 | language. |
57 | |
58 | An object belonging to a language class is called a "language |
59 | handle"; it's typically a flyweight object. |
60 | |
61 | The normal course of action is to call: |
62 | |
63 | use TkBocciBall::Localize; # the localization project class |
64 | $lh = TkBocciBall::Localize->get_handle(); |
65 | # Depending on the user's locale, etc., this will |
66 | # make a language handle from among the classes available, |
67 | # and any defaults that you declare. |
68 | die "Couldn't make a language handle??" unless $lh; |
69 | |
70 | From then on, you use the C<maketext> function to access |
71 | entries in whatever lexicon(s) belong to the language handle |
72 | you got. So, this: |
73 | |
74 | print $lh->maketext("You won!"), "\n"; |
75 | |
76 | ...emits the right text for this language. If the object |
77 | in C<$lh> belongs to class "TkBocciBall::Localize::fr" and |
78 | %TkBocciBall::Localize::fr::Lexicon contains C<("You won!" |
79 | =E<gt> "Tu as gagnE<eacute>!")>, then the above |
80 | code happily tells the user "Tu as gagnE<eacute>!". |
81 | |
82 | =head1 METHODS |
83 | |
84 | Locale::Maketext offers a variety of methods, which fall |
85 | into three categories: |
86 | |
87 | =over |
88 | |
89 | =item * |
90 | |
91 | Methods to do with constructing language handles. |
92 | |
93 | =item * |
94 | |
95 | C<maketext> and other methods to do with accessing %Lexicon data |
96 | for a given language handle. |
97 | |
98 | =item * |
99 | |
100 | Methods that you may find it handy to use, from routines of |
101 | yours that you put in %Lexicon entries. |
102 | |
103 | =back |
104 | |
105 | These are covered in the following section. |
106 | |
107 | =head2 Construction Methods |
108 | |
109 | These are to do with constructing a language handle: |
110 | |
111 | =over |
112 | |
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113 | =item * |
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114 | |
115 | $lh = YourProjClass->get_handle( ...langtags... ) || die "lg-handle?"; |
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116 | |
117 | This tries loading classes based on the language-tags you give (like |
118 | C<("en-US", "sk", "kon", "es-MX", "ja", "i-klingon")>, and for the first class |
119 | that succeeds, returns YourProjClass::I<language>->new(). |
120 | |
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121 | If it runs thru the entire given list of language-tags, and finds no classes |
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122 | for those exact terms, it then tries "superordinate" language classes. |
123 | So if no "en-US" class (i.e., YourProjClass::en_us) |
124 | was found, nor classes for anything else in that list, we then try |
125 | its superordinate, "en" (i.e., YourProjClass::en), and so on thru |
126 | the other language-tags in the given list: "es". |
127 | (The other language-tags in our example list: |
128 | happen to have no superordinates.) |
129 | |
130 | If none of those language-tags leads to loadable classes, we then |
131 | try classes derived from YourProjClass->fallback_languages() and |
132 | then if nothing comes of that, we use classes named by |
133 | YourProjClass->fallback_language_classes(). Then in the (probably |
134 | quite unlikely) event that that fails, we just return undef. |
135 | |
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136 | =item * |
137 | |
138 | $lh = YourProjClass->get_handleB<()> || die "lg-handle?"; |
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139 | |
140 | When C<get_handle> is called with an empty parameter list, magic happens: |
141 | |
142 | If C<get_handle> senses that it's running in program that was |
143 | invoked as a CGI, then it tries to get language-tags out of the |
144 | environment variable "HTTP_ACCEPT_LANGUAGE", and it pretends that |
145 | those were the languages passed as parameters to C<get_handle>. |
146 | |
147 | Otherwise (i.e., if not a CGI), this tries various OS-specific ways |
148 | to get the language-tags for the current locale/language, and then |
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149 | pretends that those were the value(s) passed to C<get_handle>. |
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150 | |
151 | Currently this OS-specific stuff consists of looking in the environment |
152 | variables "LANG" and "LANGUAGE"; and on MSWin machines (where those |
153 | variables are typically unused), this also tries using |
154 | the module Win32::Locale to get a language-tag for whatever language/locale |
155 | is currently selected in the "Regional Settings" (or "International"?) |
156 | Control Panel. I welcome further |
157 | suggestions for making this do the Right Thing under other operating |
158 | systems that support localization. |
159 | |
160 | If you're using localization in an application that keeps a configuration |
161 | file, you might consider something like this in your project class: |
162 | |
163 | sub get_handle_via_config { |
164 | my $class = $_[0]; |
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165 | my $chosen_language = $Config_settings{'language'}; |
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166 | my $lh; |
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167 | if($chosen_language) { |
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168 | $lh = $class->get_handle($chosen_language) |
169 | || die "No language handle for \"$chosen_language\" or the like"; |
170 | } else { |
171 | # Config file missing, maybe? |
172 | $lh = $class->get_handle() |
173 | || die "Can't get a language handle"; |
174 | } |
175 | return $lh; |
176 | } |
177 | |
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178 | =item * |
179 | |
180 | $lh = YourProjClass::langname->new(); |
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181 | |
182 | This constructs a language handle. You usually B<don't> call this |
183 | directly, but instead let C<get_handle> find a language class to C<use> |
184 | and to then call ->new on. |
185 | |
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186 | =item * |
187 | |
188 | $lh->init(); |
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189 | |
190 | This is called by ->new to initialize newly-constructed language handles. |
191 | If you define an init method in your class, remember that it's usually |
192 | considered a good idea to call $lh->SUPER::init in it (presumably at the |
193 | beginning), so that all classes get a chance to initialize a new object |
194 | however they see fit. |
195 | |
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196 | =item * |
197 | |
198 | YourProjClass->fallback_languages() |
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199 | |
200 | C<get_handle> appends the return value of this to the end of |
201 | whatever list of languages you pass C<get_handle>. Unless |
202 | you override this method, your project class |
203 | will inherit Locale::Maketext's C<fallback_languages>, which |
204 | currently returns C<('i-default', 'en', 'en-US')>. |
205 | ("i-default" is defined in RFC 2277). |
206 | |
207 | This method (by having it return the name |
208 | of a language-tag that has an existing language class) |
209 | can be used for making sure that |
210 | C<get_handle> will always manage to construct a language |
211 | handle (assuming your language classes are in an appropriate |
212 | @INC directory). Or you can use the next method: |
213 | |
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214 | =item * |
215 | |
216 | YourProjClass->fallback_language_classes() |
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217 | |
218 | C<get_handle> appends the return value of this to the end |
219 | of the list of classes it will try using. Unless |
220 | you override this method, your project class |
221 | will inherit Locale::Maketext's C<fallback_language_classes>, |
222 | which currently returns an empty list, C<()>. |
223 | By setting this to some value (namely, the name of a loadable |
224 | language class), you can be sure that |
225 | C<get_handle> will always manage to construct a language |
226 | handle. |
227 | |
228 | =back |
229 | |
230 | =head2 The "maketext" Method |
231 | |
232 | This is the most important method in Locale::Maketext: |
233 | |
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234 | $text = $lh->maketext(I<key>, ...parameters for this phrase...); |
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235 | |
236 | This looks in the %Lexicon of the language handle |
237 | $lh and all its superclasses, looking |
238 | for an entry whose key is the string I<key>. Assuming such |
239 | an entry is found, various things then happen, depending on the |
240 | value found: |
241 | |
242 | If the value is a scalarref, the scalar is dereferenced and returned |
243 | (and any parameters are ignored). |
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244 | |
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245 | If the value is a coderef, we return &$value($lh, ...parameters...). |
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246 | |
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247 | If the value is a string that I<doesn't> look like it's in Bracket Notation, |
248 | we return it (after replacing it with a scalarref, in its %Lexicon). |
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249 | |
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250 | If the value I<does> look like it's in Bracket Notation, then we compile |
251 | it into a sub, replace the string in the %Lexicon with the new coderef, |
252 | and then we return &$new_sub($lh, ...parameters...). |
253 | |
254 | Bracket Notation is discussed in a later section. Note |
255 | that trying to compile a string into Bracket Notation can throw |
256 | an exception if the string is not syntactically valid (say, by not |
257 | balancing brackets right.) |
258 | |
259 | Also, calling &$coderef($lh, ...parameters...) can throw any sort of |
260 | exception (if, say, code in that sub tries to divide by zero). But |
261 | a very common exception occurs when you have Bracket |
262 | Notation text that says to call a method "foo", but there is no such |
263 | method. (E.g., "You have [quaB<tn>,_1,ball]." will throw an exception |
264 | on trying to call $lh->quaB<tn>($_[1],'ball') -- you presumably meant |
265 | "quant".) C<maketext> catches these exceptions, but only to make the |
266 | error message more readable, at which point it rethrows the exception. |
267 | |
268 | An exception I<may> be thrown if I<key> is not found in any |
269 | of $lh's %Lexicon hashes. What happens if a key is not found, |
270 | is discussed in a later section, "Controlling Lookup Failure". |
271 | |
272 | Note that you might find it useful in some cases to override |
273 | the C<maketext> method with an "after method", if you want to |
274 | translate encodings, or even scripts: |
275 | |
276 | package YrProj::zh_cn; # Chinese with PRC-style glyphs |
277 | use base ('YrProj::zh_tw'); # Taiwan-style |
278 | sub maketext { |
279 | my $self = shift(@_); |
280 | my $value = $self->maketext(@_); |
281 | return Chineeze::taiwan2mainland($value); |
282 | } |
283 | |
284 | Or you may want to override it with something that traps |
285 | any exceptions, if that's critical to your program: |
286 | |
287 | sub maketext { |
288 | my($lh, @stuff) = @_; |
289 | my $out; |
290 | eval { $out = $lh->SUPER::maketext(@stuff) }; |
291 | return $out unless $@; |
292 | ...otherwise deal with the exception... |
293 | } |
294 | |
295 | Other than those two situations, I don't imagine that |
296 | it's useful to override the C<maketext> method. (If |
297 | you run into a situation where it is useful, I'd be |
298 | interested in hearing about it.) |
299 | |
300 | =over |
301 | |
302 | =item $lh->fail_with I<or> $lh->fail_with(I<PARAM>) |
303 | |
304 | =item $lh->failure_handler_auto |
305 | |
306 | These two methods are discussed in the section "Controlling |
307 | Lookup Failure". |
308 | |
309 | =back |
310 | |
311 | =head2 Utility Methods |
312 | |
313 | These are methods that you may find it handy to use, generally |
314 | from %Lexicon routines of yours (whether expressed as |
315 | Bracket Notation or not). |
316 | |
317 | =over |
318 | |
319 | =item $language->quant($number, $singular) |
320 | |
321 | =item $language->quant($number, $singular, $plural) |
322 | |
323 | =item $language->quant($number, $singular, $plural, $negative) |
324 | |
325 | This is generally meant to be called from inside Bracket Notation |
326 | (which is discussed later), as in |
327 | |
328 | "Your search matched [quant,_1,document]!" |
329 | |
330 | It's for I<quantifying> a noun (i.e., saying how much of it there is, |
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331 | while giving the correct form of it). The behavior of this method is |
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332 | handy for English and a few other Western European languages, and you |
333 | should override it for languages where it's not suitable. You can feel |
334 | free to read the source, but the current implementation is basically |
335 | as this pseudocode describes: |
336 | |
337 | if $number is 0 and there's a $negative, |
338 | return $negative; |
339 | elsif $number is 1, |
340 | return "1 $singular"; |
341 | elsif there's a $plural, |
342 | return "$number $plural"; |
343 | else |
344 | return "$number " . $singular . "s"; |
345 | # |
346 | # ...except that we actually call numf to |
347 | # stringify $number before returning it. |
348 | |
349 | So for English (with Bracket Notation) |
350 | C<"...[quant,_1,file]..."> is fine (for 0 it returns "0 files", |
351 | for 1 it returns "1 file", and for more it returns "2 files", etc.) |
352 | |
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353 | But for "directory", you'd want C<"[quant,_1,directory,directories]"> |
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354 | so that our elementary C<quant> method doesn't think that the |
355 | plural of "directory" is "directorys". And you might find that the |
356 | output may sound better if you specify a negative form, as in: |
357 | |
358 | "[quant,_1,file,files,No files] matched your query.\n" |
359 | |
360 | Remember to keep in mind verb agreement (or adjectives too, in |
361 | other languages), as in: |
362 | |
363 | "[quant,_1,document] were matched.\n" |
364 | |
365 | Because if _1 is one, you get "1 document B<were> matched". |
366 | An acceptable hack here is to do something like this: |
367 | |
368 | "[quant,_1,document was, documents were] matched.\n" |
369 | |
370 | =item $language->numf($number) |
371 | |
372 | This returns the given number formatted nicely according to |
373 | this language's conventions. Maketext's default method is |
374 | mostly to just take the normal string form of the number |
375 | (applying sprintf "%G" for only very large numbers), and then |
376 | to add commas as necessary. (Except that |
377 | we apply C<tr/,./.,/> if $language->{'numf_comma'} is true; |
378 | that's a bit of a hack that's useful for languages that express |
379 | two million as "2.000.000" and not as "2,000,000"). |
380 | |
381 | If you want anything fancier, consider overriding this with something |
382 | that uses L<Number::Format|Number::Format>, or does something else |
383 | entirely. |
384 | |
385 | Note that numf is called by quant for stringifying all quantifying |
386 | numbers. |
387 | |
388 | =item $language->sprintf($format, @items) |
389 | |
390 | This is just a wrapper around Perl's normal C<sprintf> function. |
391 | It's provided so that you can use "sprintf" in Bracket Notation: |
392 | |
393 | "Couldn't access datanode [sprintf,%10x=~[%s~],_1,_2]!\n" |
394 | |
395 | returning... |
396 | |
397 | Couldn't access datanode Stuff=[thangamabob]! |
398 | |
399 | =item $language->language_tag() |
400 | |
401 | Currently this just takes the last bit of C<ref($language)>, turns |
402 | underscores to dashes, and returns it. So if $language is |
403 | an object of class Hee::HOO::Haw::en_us, $language->language_tag() |
404 | returns "en-us". (Yes, the usual representation for that language |
405 | tag is "en-US", but case is I<never> considered meaningful in |
406 | language-tag comparison.) |
407 | |
408 | You may override this as you like; Maketext doesn't use it for |
409 | anything. |
410 | |
411 | =item $language->encoding() |
412 | |
413 | Currently this isn't used for anything, but it's provided |
414 | (with default value of |
415 | C<(ref($language) && $language-E<gt>{'encoding'})) or "iso-8859-1"> |
416 | ) as a sort of suggestion that it may be useful/necessary to |
417 | associate encodings with your language handles (whether on a |
418 | per-class or even per-handle basis.) |
419 | |
420 | =back |
421 | |
422 | =head2 Language Handle Attributes and Internals |
423 | |
424 | A language handle is a flyweight object -- i.e., it doesn't (necessarily) |
425 | carry any data of interest, other than just being a member of |
426 | whatever class it belongs to. |
427 | |
428 | A language handle is implemented as a blessed hash. Subclasses of yours |
429 | can store whatever data you want in the hash. Currently the only hash |
430 | entry used by any crucial Maketext method is "fail", so feel free to |
431 | use anything else as you like. |
432 | |
433 | B<Remember: Don't be afraid to read the Maketext source if there's |
434 | any point on which this documentation is unclear.> This documentation |
435 | is vastly longer than the module source itself. |
436 | |
437 | =over |
438 | |
439 | =back |
440 | |
441 | =head1 LANGUAGE CLASS HIERARCHIES |
442 | |
443 | These are Locale::Maketext's assumptions about the class |
444 | hierarchy formed by all your language classes: |
445 | |
446 | =over |
447 | |
448 | =item * |
449 | |
450 | You must have a project base class, which you load, and |
451 | which you then use as the first argument in |
452 | the call to YourProjClass->get_handle(...). It should derive |
453 | (whether directly or indirectly) from Locale::Maketext. |
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454 | It B<doesn't matter> how you name this class, although assuming this |
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455 | is the localization component of your Super Mega Program, |
456 | good names for your project class might be |
457 | SuperMegaProgram::Localization, SuperMegaProgram::L10N, |
458 | SuperMegaProgram::I18N, SuperMegaProgram::International, |
459 | or even SuperMegaProgram::Languages or SuperMegaProgram::Messages. |
460 | |
461 | =item * |
462 | |
463 | Language classes are what YourProjClass->get_handle will try to load. |
464 | It will look for them by taking each language-tag (B<skipping> it |
465 | if it doesn't look like a language-tag or locale-tag!), turning it to |
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466 | all lowercase, turning dashes to underscores, and appending it |
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467 | to YourProjClass . "::". So this: |
468 | |
469 | $lh = YourProjClass->get_handle( |
470 | 'en-US', 'fr', 'kon', 'i-klingon', 'i-klingon-romanized' |
471 | ); |
472 | |
473 | will try loading the classes |
474 | YourProjClass::en_us (note lowercase!), YourProjClass::fr, |
475 | YourProjClass::kon, |
476 | YourProjClass::i_klingon |
477 | and YourProjClass::i_klingon_romanized. (And it'll stop at the |
478 | first one that actually loads.) |
479 | |
480 | =item * |
481 | |
482 | I assume that each language class derives (directly or indirectly) |
483 | from your project class, and also defines its @ISA, its %Lexicon, |
484 | or both. But I anticipate no dire consequences if these assumptions |
485 | do not hold. |
486 | |
487 | =item * |
488 | |
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489 | Language classes may derive from other language classes (although they |
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490 | should have "use I<Thatclassname>" or "use base qw(I<...classes...>)"). |
491 | They may derive from the project |
492 | class. They may derive from some other class altogether. Or via |
493 | multiple inheritance, it may derive from any mixture of these. |
494 | |
495 | =item * |
496 | |
497 | I foresee no problems with having multiple inheritance in |
498 | your hierarchy of language classes. (As usual, however, Perl will |
499 | complain bitterly if you have a cycle in the hierarchy: i.e., if |
500 | any class is its own ancestor.) |
501 | |
502 | =back |
503 | |
504 | =head1 ENTRIES IN EACH LEXICON |
505 | |
506 | A typical %Lexicon entry is meant to signify a phrase, |
507 | taking some number (0 or more) of parameters. An entry |
508 | is meant to be accessed by via |
509 | a string I<key> in $lh->maketext(I<key>, ...parameters...), |
510 | which should return a string that is generally meant for |
511 | be used for "output" to the user -- regardless of whether |
512 | this actually means printing to STDOUT, writing to a file, |
513 | or putting into a GUI widget. |
514 | |
515 | While the key must be a string value (since that's a basic |
516 | restriction that Perl places on hash keys), the value in |
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517 | the lexicon can currently be of several types: |
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518 | a defined scalar, scalarref, or coderef. The use of these is |
519 | explained above, in the section 'The "maketext" Method', and |
520 | Bracket Notation for strings is discussed in the next section. |
521 | |
522 | While you can use arbitrary unique IDs for lexicon keys |
523 | (like "_min_larger_max_error"), it is often |
524 | useful for if an entry's key is itself a valid value, like |
525 | this example error message: |
526 | |
527 | "Minimum ([_1]) is larger than maximum ([_2])!\n", |
528 | |
529 | Compare this code that uses an arbitrary ID... |
530 | |
531 | die $lh->maketext( "_min_larger_max_error", $min, $max ) |
532 | if $min > $max; |
533 | |
534 | ...to this code that uses a key-as-value: |
535 | |
536 | die $lh->maketext( |
537 | "Minimum ([_1]) is larger than maximum ([_2])!\n", |
538 | $min, $max |
539 | ) if $min > $max; |
540 | |
541 | The second is, in short, more readable. In particular, it's obvious |
542 | that the number of parameters you're feeding to that phrase (two) is |
543 | the number of parameters that it I<wants> to be fed. (Since you see |
544 | _1 and a _2 being used in the key there.) |
545 | |
546 | Also, once a project is otherwise |
547 | complete and you start to localize it, you can scrape together |
548 | all the various keys you use, and pass it to a translator; and then |
549 | the translator's work will go faster if what he's presented is this: |
550 | |
551 | "Minimum ([_1]) is larger than maximum ([_2])!\n", |
552 | => "", # fill in something here, Jacques! |
553 | |
554 | rather than this more cryptic mess: |
555 | |
556 | "_min_larger_max_error" |
557 | => "", # fill in something here, Jacques |
558 | |
559 | I think that keys as lexicon values makes the completed lexicon |
560 | entries more readable: |
561 | |
562 | "Minimum ([_1]) is larger than maximum ([_2])!\n", |
563 | => "Le minimum ([_1]) est plus grand que le maximum ([_2])!\n", |
564 | |
565 | Also, having valid values as keys becomes very useful if you set |
566 | up an _AUTO lexicon. _AUTO lexicons are discussed in a later |
567 | section. |
568 | |
569 | I almost always use keys that are themselves |
570 | valid lexicon values. One notable exception is when the value is |
571 | quite long. For example, to get the screenful of data that |
f666394a |
572 | a command-line program might return when given an unknown switch, |
573 | I often just use a brief, self-explanatory key such as "_USAGE_MESSAGE". At that point I then go |
9378c581 |
574 | and immediately to define that lexicon entry in the |
575 | ProjectClass::L10N::en lexicon (since English is always my "project |
f918d677 |
576 | language"): |
9378c581 |
577 | |
578 | '_USAGE_MESSAGE' => <<'EOSTUFF', |
579 | ...long long message... |
580 | EOSTUFF |
581 | |
582 | and then I can use it as: |
583 | |
584 | getopt('oDI', \%opts) or die $lh->maketext('_USAGE_MESSAGE'); |
585 | |
586 | Incidentally, |
587 | note that each class's C<%Lexicon> inherits-and-extends |
588 | the lexicons in its superclasses. This is not because these are |
589 | special hashes I<per se>, but because you access them via the |
590 | C<maketext> method, which looks for entries across all the |
f666394a |
591 | C<%Lexicon> hashes in a language class I<and> all its ancestor classes. |
9378c581 |
592 | (This is because the idea of "class data" isn't directly implemented |
593 | in Perl, but is instead left to individual class-systems to implement |
594 | as they see fit..) |
595 | |
596 | Note that you may have things stored in a lexicon |
597 | besides just phrases for output: for example, if your program |
598 | takes input from the keyboard, asking a "(Y/N)" question, |
f666394a |
599 | you probably need to know what the equivalent of "Y[es]/N[o]" is |
9378c581 |
600 | in whatever language. You probably also need to know what |
601 | the equivalents of the answers "y" and "n" are. You can |
602 | store that information in the lexicon (say, under the keys |
603 | "~answer_y" and "~answer_n", and the long forms as |
604 | "~answer_yes" and "~answer_no", where "~" is just an ad-hoc |
605 | character meant to indicate to programmers/translators that |
606 | these are not phrases for output). |
607 | |
608 | Or instead of storing this in the language class's lexicon, |
609 | you can (and, in some cases, really should) represent the same bit |
f666394a |
610 | of knowledge as code in a method in the language class. (That |
9378c581 |
611 | leaves a tidy distinction between the lexicon as the things we |
612 | know how to I<say>, and the rest of the things in the lexicon class |
613 | as things that we know how to I<do>.) Consider |
614 | this example of a processor for responses to French "oui/non" |
615 | questions: |
616 | |
617 | sub y_or_n { |
618 | return undef unless defined $_[1] and length $_[1]; |
619 | my $answer = lc $_[1]; # smash case |
620 | return 1 if $answer eq 'o' or $answer eq 'oui'; |
621 | return 0 if $answer eq 'n' or $answer eq 'non'; |
622 | return undef; |
623 | } |
624 | |
625 | ...which you'd then call in a construct like this: |
626 | |
627 | my $response; |
628 | until(defined $response) { |
629 | print $lh->maketext("Open the pod bay door (y/n)? "); |
630 | $response = $lh->y_or_n( get_input_from_keyboard_somehow() ); |
631 | } |
632 | if($response) { $pod_bay_door->open() } |
633 | else { $pod_bay_door->leave_closed() } |
634 | |
635 | Other data worth storing in a lexicon might be things like |
636 | filenames for language-targetted resources: |
637 | |
638 | ... |
639 | "_main_splash_png" |
640 | => "/styles/en_us/main_splash.png", |
641 | "_main_splash_imagemap" |
642 | => "/styles/en_us/main_splash.incl", |
643 | "_general_graphics_path" |
644 | => "/styles/en_us/", |
645 | "_alert_sound" |
646 | => "/styles/en_us/hey_there.wav", |
647 | "_forward_icon" |
648 | => "left_arrow.png", |
649 | "_backward_icon" |
650 | => "right_arrow.png", |
651 | # In some other languages, left equals |
652 | # BACKwards, and right is FOREwards. |
653 | ... |
654 | |
655 | You might want to do the same thing for expressing key bindings |
656 | or the like (since hardwiring "q" as the binding for the function |
657 | that quits a screen/menu/program is useful only if your language |
658 | happens to associate "q" with "quit"!) |
659 | |
660 | =head1 BRACKET NOTATION |
661 | |
662 | Bracket Notation is a crucial feature of Locale::Maketext. I mean |
f666394a |
663 | Bracket Notation to provide a replacement for the use of sprintf formatting. |
9378c581 |
664 | Everything you do with Bracket Notation could be done with a sub block, |
665 | but bracket notation is meant to be much more concise. |
666 | |
667 | Bracket Notation is a like a miniature "template" system (in the sense |
668 | of L<Text::Template|Text::Template>, not in the sense of C++ templates), |
f666394a |
669 | where normal text is passed thru basically as is, but text in special |
670 | regions is specially interpreted. In Bracket Notation, you use square brackets ("[...]"), |
671 | not curly braces ("{...}") to note sections that are specially interpreted. |
9378c581 |
672 | |
673 | For example, here all the areas that are taken literally are underlined with |
674 | a "^", and all the in-bracket special regions are underlined with an X: |
675 | |
676 | "Minimum ([_1]) is larger than maximum ([_2])!\n", |
677 | ^^^^^^^^^ XX ^^^^^^^^^^^^^^^^^^^^^^^^^^ XX ^^^^ |
678 | |
679 | When that string is compiled from bracket notation into a real Perl sub, |
680 | it's basically turned into: |
681 | |
682 | sub { |
683 | my $lh = $_[0]; |
684 | my @params = @_; |
685 | return join '', |
686 | "Minimum (", |
687 | ...some code here... |
688 | ") is larger than maximum (", |
689 | ...some code here... |
690 | ")!\n", |
691 | } |
692 | # to be called by $lh->maketext(KEY, params...) |
693 | |
694 | In other words, text outside bracket groups is turned into string |
695 | literals. Text in brackets is rather more complex, and currently follows |
696 | these rules: |
697 | |
698 | =over |
699 | |
700 | =item * |
701 | |
702 | Bracket groups that are empty, or which consist only of whitespace, |
703 | are ignored. (Examples: "[]", "[ ]", or a [ and a ] with returns |
704 | and/or tabs and/or spaces between them. |
705 | |
706 | Otherwise, each group is taken to be a comma-separated group of items, |
707 | and each item is interpreted as follows: |
708 | |
709 | =item * |
710 | |
711 | An item that is "_I<digits>" or "_-I<digits>" is interpreted as |
f666394a |
712 | $_[I<value>]. I.e., "_1" becomes with $_[1], and "_-3" is interpreted |
9378c581 |
713 | as $_[-3] (in which case @_ should have at least three elements in it). |
714 | Note that $_[0] is the language handle, and is typically not named |
715 | directly. |
716 | |
717 | =item * |
718 | |
719 | An item "_*" is interpreted to mean "all of @_ except $_[0]". |
720 | I.e., C<@_[1..$#_]>. Note that this is an empty list in the case |
721 | of calls like $lh->maketext(I<key>) where there are no |
722 | parameters (except $_[0], the language handle). |
723 | |
724 | =item * |
725 | |
726 | Otherwise, each item is interpreted as a string literal. |
727 | |
728 | =back |
729 | |
730 | The group as a whole is interpreted as follows: |
731 | |
732 | =over |
733 | |
734 | =item * |
735 | |
736 | If the first item in a bracket group looks like a method name, |
737 | then that group is interpreted like this: |
738 | |
739 | $lh->that_method_name( |
740 | ...rest of items in this group... |
741 | ), |
742 | |
743 | =item * |
744 | |
ff5ad48a |
745 | If the first item in a bracket group is "*", it's taken as shorthand |
746 | for the so commonly called "quant" method. Similarly, if the first |
747 | item in a bracket group is "#", it's taken to be shorthand for |
748 | "numf". |
749 | |
750 | =item * |
751 | |
f666394a |
752 | If the first item in a bracket group is the empty-string, or "_*" |
9378c581 |
753 | or "_I<digits>" or "_-I<digits>", then that group is interpreted |
754 | as just the interpolation of all its items: |
755 | |
756 | join('', |
757 | ...rest of items in this group... |
758 | ), |
759 | |
760 | Examples: "[_1]" and "[,_1]", which are synonymous; and |
f918d677 |
761 | "C<[,ID-(,_4,-,_2,)]>", which compiles as |
9378c581 |
762 | C<join "", "ID-(", $_[4], "-", $_[2], ")">. |
763 | |
764 | =item * |
765 | |
766 | Otherwise this bracket group is invalid. For example, in the group |
f666394a |
767 | "[!@#,whatever]", the first item C<"!@#"> is neither the empty-string, |
9378c581 |
768 | "_I<number>", "_-I<number>", "_*", nor a valid method name; and so |
769 | Locale::Maketext will throw an exception of you try compiling an |
770 | expression containing this bracket group. |
771 | |
772 | =back |
773 | |
774 | Note, incidentally, that items in each group are comma-separated, |
775 | not C</\s*,\s*/>-separated. That is, you might expect that this |
776 | bracket group: |
777 | |
778 | "Hoohah [foo, _1 , bar ,baz]!" |
779 | |
780 | would compile to this: |
781 | |
782 | sub { |
783 | my $lh = $_[0]; |
784 | return join '', |
785 | "Hoohah ", |
786 | $lh->foo( $_[1], "bar", "baz"), |
787 | "!", |
788 | } |
789 | |
790 | But it actually compiles as this: |
791 | |
792 | sub { |
793 | my $lh = $_[0]; |
794 | return join '', |
795 | "Hoohah ", |
f666394a |
796 | $lh->foo(" _1 ", " bar ", "baz"), # note the <space> in " bar " |
9378c581 |
797 | "!", |
798 | } |
799 | |
800 | In the notation discussed so far, the characters "[" and "]" are given |
801 | special meaning, for opening and closing bracket groups, and "," has |
802 | a special meaning inside bracket groups, where it separates items in the |
803 | group. This begs the question of how you'd express a literal "[" or |
804 | "]" in a Bracket Notation string, and how you'd express a literal |
805 | comma inside a bracket group. For this purpose I've adopted "~" (tilde) |
806 | as an escape character: "~[" means a literal '[' character anywhere |
807 | in Bracket Notation (i.e., regardless of whether you're in a bracket |
808 | group or not), and ditto for "~]" meaning a literal ']', and "~," meaning |
809 | a literal comma. (Altho "," means a literal comma outside of |
810 | bracket groups -- it's only inside bracket groups that commas are special.) |
811 | |
812 | And on the off chance you need a literal tilde in a bracket expression, |
813 | you get it with "~~". |
814 | |
815 | Currently, an unescaped "~" before a character |
816 | other than a bracket or a comma is taken to mean just a "~" and that |
f918d677 |
817 | character. I.e., "~X" means the same as "~~X" -- i.e., one literal tilde, |
9378c581 |
818 | and then one literal "X". However, by using "~X", you are assuming that |
819 | no future version of Maketext will use "~X" as a magic escape sequence. |
820 | In practice this is not a great problem, since first off you can just |
821 | write "~~X" and not worry about it; second off, I doubt I'll add lots |
822 | of new magic characters to bracket notation; and third off, you |
823 | aren't likely to want literal "~" characters in your messages anyway, |
824 | since it's not a character with wide use in natural language text. |
825 | |
826 | Brackets must be balanced -- every openbracket must have |
827 | one matching closebracket, and vice versa. So these are all B<invalid>: |
828 | |
829 | "I ate [quant,_1,rhubarb pie." |
830 | "I ate [quant,_1,rhubarb pie[." |
831 | "I ate quant,_1,rhubarb pie]." |
832 | "I ate quant,_1,rhubarb pie[." |
833 | |
834 | Currently, bracket groups do not nest. That is, you B<cannot> say: |
835 | |
836 | "Foo [bar,baz,[quux,quuux]]\n"; |
837 | |
838 | If you need a notation that's that powerful, use normal Perl: |
839 | |
840 | %Lexicon = ( |
841 | ... |
842 | "some_key" => sub { |
843 | my $lh = $_[0]; |
844 | join '', |
845 | "Foo ", |
846 | $lh->bar('baz', $lh->quux('quuux')), |
847 | "\n", |
848 | }, |
849 | ... |
850 | ); |
851 | |
852 | Or write the "bar" method so you don't need to pass it the |
853 | output from calling quux. |
854 | |
855 | I do not anticipate that you will need (or particularly want) |
856 | to nest bracket groups, but you are welcome to email me with |
857 | convincing (real-life) arguments to the contrary. |
858 | |
859 | =head1 AUTO LEXICONS |
860 | |
861 | If maketext goes to look in an individual %Lexicon for an entry |
862 | for I<key> (where I<key> does not start with an underscore), and |
863 | sees none, B<but does see> an entry of "_AUTO" => I<some_true_value>, |
864 | then we actually define $Lexicon{I<key>} = I<key> right then and there, |
865 | and then use that value as if it had been there all |
866 | along. This happens before we even look in any superclass %Lexicons! |
867 | |
868 | (This is meant to be somewhat like the AUTOLOAD mechanism in |
869 | Perl's function call system -- or, looked at another way, |
870 | like the L<AutoLoader|AutoLoader> module.) |
871 | |
872 | I can picture all sorts of circumstances where you just |
873 | do not want lookup to be able to fail (since failing |
f666394a |
874 | normally means that maketext throws a C<die>, although |
9378c581 |
875 | see the next section for greater control over that). But |
876 | here's one circumstance where _AUTO lexicons are meant to |
877 | be I<especially> useful: |
878 | |
879 | As you're writing an application, you decide as you go what messages |
880 | you need to emit. Normally you'd go to write this: |
881 | |
882 | if(-e $filename) { |
883 | go_process_file($filename) |
884 | } else { |
f666394a |
885 | print qq{Couldn't find file "$filename"!\n}; |
9378c581 |
886 | } |
887 | |
888 | but since you anticipate localizing this, you write: |
889 | |
890 | use ThisProject::I18N; |
891 | my $lh = ThisProject::I18N->get_handle(); |
892 | # For the moment, assume that things are set up so |
893 | # that we load class ThisProject::I18N::en |
f918d677 |
894 | # and that that's the class that $lh belongs to. |
9378c581 |
895 | ... |
896 | if(-e $filename) { |
897 | go_process_file($filename) |
898 | } else { |
899 | print $lh->maketext( |
f666394a |
900 | qq{Couldn't find file "[_1]"!\n}, $filename |
9378c581 |
901 | ); |
902 | } |
903 | |
904 | Now, right after you've just written the above lines, you'd |
905 | normally have to go open the file |
906 | ThisProject/I18N/en.pm, and immediately add an entry: |
907 | |
908 | "Couldn't find file \"[_1]\"!\n" |
909 | => "Couldn't find file \"[_1]\"!\n", |
910 | |
911 | But I consider that somewhat of a distraction from the work |
912 | of getting the main code working -- to say nothing of the fact |
913 | that I often have to play with the program a few times before |
914 | I can decide exactly what wording I want in the messages (which |
915 | in this case would require me to go changing three lines of code: |
916 | the call to maketext with that key, and then the two lines in |
917 | ThisProject/I18N/en.pm). |
918 | |
919 | However, if you set "_AUTO => 1" in the %Lexicon in, |
920 | ThisProject/I18N/en.pm (assuming that English (en) is |
921 | the language that all your programmers will be using for this |
922 | project's internal message keys), then you don't ever have to |
923 | go adding lines like this |
924 | |
925 | "Couldn't find file \"[_1]\"!\n" |
926 | => "Couldn't find file \"[_1]\"!\n", |
927 | |
928 | to ThisProject/I18N/en.pm, because if _AUTO is true there, |
929 | then just looking for an entry with the key "Couldn't find |
930 | file \"[_1]\"!\n" in that lexicon will cause it to be added, |
931 | with that value! |
932 | |
933 | Note that the reason that keys that start with "_" |
934 | are immune to _AUTO isn't anything generally magical about |
935 | the underscore character -- I just wanted a way to have most |
936 | lexicon keys be autoable, except for possibly a few, and I |
937 | arbitrarily decided to use a leading underscore as a signal |
938 | to distinguish those few. |
939 | |
940 | =head1 CONTROLLING LOOKUP FAILURE |
941 | |
942 | If you call $lh->maketext(I<key>, ...parameters...), |
943 | and there's no entry I<key> in $lh's class's %Lexicon, nor |
944 | in the superclass %Lexicon hash, I<and> if we can't auto-make |
945 | I<key> (because either it starts with a "_", or because none |
946 | of its lexicons have C<_AUTO =E<gt> 1,>), then we have |
947 | failed to find a normal way to maketext I<key>. What then |
f666394a |
948 | happens in these failure conditions, depends on the $lh object's |
9378c581 |
949 | "fail" attribute. |
950 | |
951 | If the language handle has no "fail" attribute, maketext |
952 | will simply throw an exception (i.e., it calls C<die>, mentioning |
953 | the I<key> whose lookup failed, and naming the line number where |
954 | the calling $lh->maketext(I<key>,...) was. |
955 | |
956 | If the language handle has a "fail" attribute whose value is a |
957 | coderef, then $lh->maketext(I<key>,...params...) gives up and calls: |
958 | |
f666394a |
959 | return $that_subref->($lh, $key, @params); |
9378c581 |
960 | |
961 | Otherwise, the "fail" attribute's value should be a string denoting |
962 | a method name, so that $lh->maketext(I<key>,...params...) can |
963 | give up with: |
964 | |
965 | return $lh->$that_method_name($phrase, @params); |
966 | |
967 | The "fail" attribute can be accessed with the C<fail_with> method: |
968 | |
969 | # Set to a coderef: |
970 | $lh->fail_with( \&failure_handler ); |
971 | |
972 | # Set to a method name: |
973 | $lh->fail_with( 'failure_method' ); |
974 | |
975 | # Set to nothing (i.e., so failure throws a plain exception) |
976 | $lh->fail_with( undef ); |
977 | |
f666394a |
978 | # Get the current value |
9378c581 |
979 | $handler = $lh->fail_with(); |
980 | |
981 | Now, as to what you may want to do with these handlers: Maybe you'd |
982 | want to log what key failed for what class, and then die. Maybe |
983 | you don't like C<die> and instead you want to send the error message |
984 | to STDOUT (or wherever) and then merely C<exit()>. |
985 | |
986 | Or maybe you don't want to C<die> at all! Maybe you could use a |
987 | handler like this: |
988 | |
989 | # Make all lookups fall back onto an English value, |
f666394a |
990 | # but only after we log it for later fingerpointing. |
9378c581 |
991 | my $lh_backup = ThisProject->get_handle('en'); |
992 | open(LEX_FAIL_LOG, ">>wherever/lex.log") || die "GNAARGH $!"; |
993 | sub lex_fail { |
994 | my($failing_lh, $key, $params) = @_; |
995 | print LEX_FAIL_LOG scalar(localtime), "\t", |
996 | ref($failing_lh), "\t", $key, "\n"; |
997 | return $lh_backup->maketext($key,@params); |
998 | } |
999 | |
1000 | Some users have expressed that they think this whole mechanism of |
1001 | having a "fail" attribute at all, seems a rather pointless complication. |
1002 | But I want Locale::Maketext to be usable for software projects of I<any> |
1003 | scale and type; and different software projects have different ideas |
1004 | of what the right thing is to do in failure conditions. I could simply |
1005 | say that failure always throws an exception, and that if you want to be |
1006 | careful, you'll just have to wrap every call to $lh->maketext in an |
1007 | S<eval { }>. However, I want programmers to reserve the right (via |
1008 | the "fail" attribute) to treat lookup failure as something other than |
1009 | an exception of the same level of severity as a config file being |
f918d677 |
1010 | unreadable, or some essential resource being inaccessible. |
9378c581 |
1011 | |
1012 | One possibly useful value for the "fail" attribute is the method name |
f666394a |
1013 | "failure_handler_auto". This is a method defined in the class |
9378c581 |
1014 | Locale::Maketext itself. You set it with: |
1015 | |
1016 | $lh->fail_with('failure_handler_auto'); |
1017 | |
1018 | Then when you call $lh->maketext(I<key>, ...parameters...) and |
1019 | there's no I<key> in any of those lexicons, maketext gives up with |
1020 | |
1021 | return $lh->failure_handler_auto($key, @params); |
1022 | |
1023 | But failure_handler_auto, instead of dying or anything, compiles |
f666394a |
1024 | $key, caching it in |
1025 | |
1026 | $lh->{'failure_lex'}{$key} = $complied |
1027 | |
9378c581 |
1028 | and then calls the compiled value, and returns that. (I.e., if |
1029 | $key looks like bracket notation, $compiled is a sub, and we return |
1030 | &{$compiled}(@params); but if $key is just a plain string, we just |
1031 | return that.) |
1032 | |
1033 | The effect of using "failure_auto_handler" |
1034 | is like an AUTO lexicon, except that it 1) compiles $key even if |
1035 | it starts with "_", and 2) you have a record in the new hashref |
1036 | $lh->{'failure_lex'} of all the keys that have failed for |
1037 | this object. This should avoid your program dying -- as long |
1038 | as your keys aren't actually invalid as bracket code, and as |
1039 | long as they don't try calling methods that don't exist. |
1040 | |
1041 | "failure_auto_handler" may not be exactly what you want, but I |
1042 | hope it at least shows you that maketext failure can be mitigated |
1043 | in any number of very flexible ways. If you can formalize exactly |
1044 | what you want, you should be able to express that as a failure |
1045 | handler. You can even make it default for every object of a given |
1046 | class, by setting it in that class's init: |
1047 | |
1048 | sub init { |
1049 | my $lh = $_[0]; # a newborn handle |
1050 | $lh->SUPER::init(); |
1051 | $lh->fail_with('my_clever_failure_handler'); |
1052 | return; |
1053 | } |
1054 | sub my_clever_failure_handler { |
1055 | ...you clever things here... |
1056 | } |
1057 | |
1058 | =head1 HOW TO USE MAKETEXT |
1059 | |
1060 | Here is a brief checklist on how to use Maketext to localize |
1061 | applications: |
1062 | |
1063 | =over |
1064 | |
1065 | =item * |
1066 | |
1067 | Decide what system you'll use for lexicon keys. If you insist, |
1068 | you can use opaque IDs (if you're nostalgic for C<catgets>), |
1069 | but I have better suggestions in the |
1070 | section "Entries in Each Lexicon", above. Assuming you opt for |
1071 | meaningful keys that double as values (like "Minimum ([_1]) is |
1072 | larger than maximum ([_2])!\n"), you'll have to settle on what |
1073 | language those should be in. For the sake of argument, I'll |
1074 | call this English, specifically American English, "en-US". |
1075 | |
1076 | =item * |
1077 | |
1078 | Create a class for your localization project. This is |
1079 | the name of the class that you'll use in the idiom: |
1080 | |
1081 | use Projname::L10N; |
1082 | my $lh = Projname::L10N->get_handle(...) || die "Language?"; |
1083 | |
f666394a |
1084 | Assuming you call your class Projname::L10N, create a class |
9378c581 |
1085 | consisting minimally of: |
1086 | |
1087 | package Projname::L10N; |
1088 | use base qw(Locale::Maketext); |
1089 | ...any methods you might want all your languages to share... |
1090 | |
1091 | # And, assuming you want the base class to be an _AUTO lexicon, |
1092 | # as is discussed a few sections up: |
1093 | |
1094 | 1; |
1095 | |
1096 | =item * |
1097 | |
1098 | Create a class for the language your internal keys are in. Name |
1099 | the class after the language-tag for that language, in lowercase, |
1100 | with dashes changed to underscores. Assuming your project's first |
1101 | language is US English, you should call this Projname::L10N::en_us. |
1102 | It should consist minimally of: |
1103 | |
1104 | package Projname::L10N::en_us; |
1105 | use base qw(Projname::L10N); |
1106 | %Lexicon = ( |
1107 | '_AUTO' => 1, |
1108 | ); |
1109 | 1; |
1110 | |
1111 | (For the rest of this section, I'll assume that this "first |
1112 | language class" of Projname::L10N::en_us has |
1113 | _AUTO lexicon.) |
1114 | |
1115 | =item * |
1116 | |
1117 | Go and write your program. Everywhere in your program where |
1118 | you would say: |
1119 | |
1120 | print "Foobar $thing stuff\n"; |
1121 | |
1122 | instead do it thru maketext, using no variable interpolation in |
1123 | the key: |
1124 | |
1125 | print $lh->maketext("Foobar [_1] stuff\n", $thing); |
1126 | |
1127 | If you get tired of constantly saying C<print $lh-E<gt>maketext>, |
1128 | consider making a functional wrapper for it, like so: |
1129 | |
1130 | use Projname::L10N; |
1131 | use vars qw($lh); |
1132 | $lh = Projname::L10N->get_handle(...) || die "Language?"; |
1133 | sub pmt (@) { print( $lh->maketext(@_)) } |
1134 | # "pmt" is short for "Print MakeText" |
1135 | $Carp::Verbose = 1; |
1136 | # so if maketext fails, we see made the call to pmt |
1137 | |
1138 | Besides whole phrases meant for output, anything language-dependent |
1139 | should be put into the class Projname::L10N::en_us, |
1140 | whether as methods, or as lexicon entries -- this is discussed |
1141 | in the section "Entries in Each Lexicon", above. |
1142 | |
1143 | =item * |
1144 | |
1145 | Once the program is otherwise done, and once its localization for |
1146 | the first language works right (via the data and methods in |
1147 | Projname::L10N::en_us), you can get together the data for translation. |
1148 | If your first language lexicon isn't an _AUTO lexicon, then you already |
1149 | have all the messages explicitly in the lexicon (or else you'd be |
1150 | getting exceptions thrown when you call $lh->maketext to get |
1151 | messages that aren't in there). But if you were (advisedly) lazy and are |
1152 | using an _AUTO lexicon, then you've got to make a list of all the phrases |
1153 | that you've so far been letting _AUTO generate for you. There are very |
1154 | many ways to assemble such a list. The most straightforward is to simply |
1155 | grep the source for every occurrence of "maketext" (or calls |
1156 | to wrappers around it, like the above C<pmt> function), and to log the |
1157 | following phrase. |
1158 | |
1159 | =item * |
1160 | |
f666394a |
1161 | You may at this point want to consider whether your base class |
1162 | (Projname::L10N), from which all lexicons inherit from (Projname::L10N::en, |
1163 | Projname::L10N::es, etc.), should be an _AUTO lexicon. It may be true |
9378c581 |
1164 | that in theory, all needed messages will be in each language class; |
1165 | but in the presumably unlikely or "impossible" case of lookup failure, |
1166 | you should consider whether your program should throw an exception, |
1167 | emit text in English (or whatever your project's first language is), |
1168 | or some more complex solution as described in the section |
1169 | "Controlling Lookup Failure", above. |
1170 | |
1171 | =item * |
1172 | |
1173 | Submit all messages/phrases/etc. to translators. |
1174 | |
1175 | (You may, in fact, want to start with localizing to I<one> other language |
f666394a |
1176 | at first, if you're not sure that you've properly abstracted the |
9378c581 |
1177 | language-dependent parts of your code.) |
1178 | |
1179 | Translators may request clarification of the situation in which a |
1180 | particular phrase is found. For example, in English we are entirely happy |
1181 | saying "I<n> files found", regardless of whether we mean "I looked for files, |
1182 | and found I<n> of them" or the rather distinct situation of "I looked for |
1183 | something else (like lines in files), and along the way I saw I<n> |
1184 | files." This may involve rethinking things that you thought quite clear: |
1185 | should "Edit" on a toolbar be a noun ("editing") or a verb ("to edit")? Is |
1186 | there already a conventionalized way to express that menu option, separate |
1187 | from the target language's normal word for "to edit"? |
1188 | |
1189 | In all cases where the very common phenomenon of quantification |
1190 | (saying "I<N> files", for B<any> value of N) |
1191 | is involved, each translator should make clear what dependencies the |
1192 | number causes in the sentence. In many cases, dependency is |
1193 | limited to words adjacent to the number, in places where you might |
1194 | expect them ("I found the-?PLURAL I<N> |
1195 | empty-?PLURAL directory-?PLURAL"), but in some cases there are |
1196 | unexpected dependencies ("I found-?PLURAL ..."!) as well as long-distance |
1197 | dependencies "The I<N> directory-?PLURAL could not be deleted-?PLURAL"!). |
1198 | |
1199 | Remind the translators to consider the case where N is 0: |
1200 | "0 files found" isn't exactly natural-sounding in any language, but it |
1201 | may be unacceptable in many -- or it may condition special |
1202 | kinds of agreement (similar to English "I didN'T find ANY files"). |
1203 | |
1204 | Remember to ask your translators about numeral formatting in their |
1205 | language, so that you can override the C<numf> method as |
1206 | appropriate. Typical variables in number formatting are: what to |
1207 | use as a decimal point (comma? period?); what to use as a thousands |
f918d677 |
1208 | separator (space? nonbreaking space? comma? period? small |
9378c581 |
1209 | middot? prime? apostrophe?); and even whether the so-called "thousands |
1210 | separator" is actually for every third digit -- I've heard reports of |
f918d677 |
1211 | two hundred thousand being expressible as "2,00,000" for some Indian |
9378c581 |
1212 | (Subcontinental) languages, besides the less surprising "S<200 000>", |
1213 | "200.000", "200,000", and "200'000". Also, using a set of numeral |
1214 | glyphs other than the usual ASCII "0"-"9" might be appreciated, as via |
1215 | C<tr/0-9/\x{0966}-\x{096F}/> for getting digits in Devanagari script |
1216 | (for Hindi, Konkani, others). |
1217 | |
1218 | The basic C<quant> method that Locale::Maketext provides should be |
1219 | good for many languages. For some languages, it might be useful |
1220 | to modify it (or its constituent C<numerate> method) |
1221 | to take a plural form in the two-argument call to C<quant> |
1222 | (as in "[quant,_1,files]") if |
1223 | it's all-around easier to infer the singular form from the plural, than |
1224 | to infer the plural form from the singular. |
1225 | |
1226 | But for other languages (as is discussed at length |
1227 | in L<Locale::Maketext::TPJ13|Locale::Maketext::TPJ13>), simple |
1228 | C<quant>/C<numerify> is not enough. For the particularly problematic |
1229 | Slavic languages, what you may need is a method which you provide |
1230 | with the number, the citation form of the noun to quantify, and |
1231 | the case and gender that the sentence's syntax projects onto that |
1232 | noun slot. The method would then be responsible for determining |
1233 | what grammatical number that numeral projects onto its noun phrase, |
1234 | and what case and gender it may override the normal case and gender |
1235 | with; and then it would look up the noun in a lexicon providing |
1236 | all needed inflected forms. |
1237 | |
1238 | =item * |
1239 | |
1240 | You may also wish to discuss with the translators the question of |
1241 | how to relate different subforms of the same language tag, |
1242 | considering how this reacts with C<get_handle>'s treatment of |
1243 | these. For example, if a user accepts interfaces in "en, fr", and |
1244 | you have interfaces available in "en-US" and "fr", what should |
1245 | they get? You may wish to resolve this by establishing that "en" |
1246 | and "en-US" are effectively synonymous, by having one class |
1247 | zero-derive from the other. |
1248 | |
1249 | For some languages this issue may never come up (Danish is rarely |
1250 | expressed as "da-DK", but instead is just "da"). And for other |
1251 | languages, the whole concept of a "generic" form may verge on |
1252 | being uselessly vague, particularly for interfaces involving voice |
1253 | media in forms of Arabic or Chinese. |
1254 | |
1255 | =item * |
1256 | |
1257 | Once you've localized your program/site/etc. for all desired |
1258 | languages, be sure to show the result (whether live, or via |
1259 | screenshots) to the translators. Once they approve, make every |
1260 | effort to have it then checked by at least one other speaker of |
1261 | that language. This holds true even when (or especially when) the |
1262 | translation is done by one of your own programmers. Some |
1263 | kinds of systems may be harder to find testers for than others, |
1264 | depending on the amount of domain-specific jargon and concepts |
1265 | involved -- it's easier to find people who can tell you whether |
1266 | they approve of your translation for "delete this message" in an |
1267 | email-via-Web interface, than to find people who can give you |
1268 | an informed opinion on your translation for "attribute value" |
1269 | in an XML query tool's interface. |
1270 | |
1271 | =back |
1272 | |
1273 | =head1 SEE ALSO |
1274 | |
1275 | I recommend reading all of these: |
1276 | |
1277 | L<Locale::Maketext::TPJ13|Locale::Maketext::TPJ13> -- my I<The Perl |
1278 | Journal> article about Maketext. It explains many important concepts |
1279 | underlying Locale::Maketext's design, and some insight into why |
f666394a |
1280 | Maketext is better than the plain old approach of having |
9378c581 |
1281 | message catalogs that are just databases of sprintf formats. |
1282 | |
1283 | L<File::Findgrep|File::Findgrep> is a sample application/module |
f918d677 |
1284 | that uses Locale::Maketext to localize its messages. For a larger |
1285 | internationalized system, see also L<Apache::MP3>. |
9378c581 |
1286 | |
1287 | L<I18N::LangTags|I18N::LangTags>. |
1288 | |
1289 | L<Win32::Locale|Win32::Locale>. |
1290 | |
1291 | RFC 3066, I<Tags for the Identification of Languages>, |
1292 | as at http://sunsite.dk/RFC/rfc/rfc3066.html |
1293 | |
1294 | RFC 2277, I<IETF Policy on Character Sets and Languages> |
1295 | is at http://sunsite.dk/RFC/rfc/rfc2277.html -- much of it is |
1296 | just things of interest to protocol designers, but it explains |
1297 | some basic concepts, like the distinction between locales and |
1298 | language-tags. |
1299 | |
1300 | The manual for GNU C<gettext>. The gettext dist is available in |
1301 | C<ftp://prep.ai.mit.edu/pub/gnu/> -- get |
1302 | a recent gettext tarball and look in its "doc/" directory, there's |
1303 | an easily browsable HTML version in there. The |
1304 | gettext documentation asks lots of questions worth thinking |
1305 | about, even if some of their answers are sometimes wonky, |
1306 | particularly where they start talking about pluralization. |
1307 | |
1308 | The Locale/Maketext.pm source. Obverse that the module is much |
1309 | shorter than its documentation! |
1310 | |
1311 | =head1 COPYRIGHT AND DISCLAIMER |
1312 | |
14be35aa |
1313 | Copyright (c) 1999-2004 Sean M. Burke. All rights reserved. |
9378c581 |
1314 | |
1315 | This library is free software; you can redistribute it and/or modify |
1316 | it under the same terms as Perl itself. |
1317 | |
1318 | This program is distributed in the hope that it will be useful, but |
1319 | without any warranty; without even the implied warranty of |
1320 | merchantability or fitness for a particular purpose. |
1321 | |
1322 | =head1 AUTHOR |
1323 | |
1324 | Sean M. Burke C<sburke@cpan.org> |
1325 | |
1326 | =cut |