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1 | |
2 | # Time-stamp: "2001-05-25 07:50:08 MDT" |
3 | |
4 | =head1 NAME |
5 | |
6 | Locale::Maketext -- framework for localization |
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 | |
c4ea979c |
113 | =item * |
114 | |
115 | $lh = YourProjClass->get_handle( ...langtags... ) || die "lg-handle?"; |
9378c581 |
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 | |
121 | It runs thru the entire given list of language-tags, and finds no classes |
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 | |
c4ea979c |
136 | =item * |
137 | |
138 | $lh = YourProjClass->get_handleB<()> || die "lg-handle?"; |
9378c581 |
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 |
149 | pretends that those were the value(s) passed to C<cet_handle>. |
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]; |
165 | my $preferred_language = $Config_settings{'language'}; |
166 | my $lh; |
167 | if($preferred_language) { |
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 | |
178 | =item $lh = YourProjClass::langname->new(); |
179 | |
180 | This constructs a language handle. You usually B<don't> call this |
181 | directly, but instead let C<get_handle> find a language class to C<use> |
182 | and to then call ->new on. |
183 | |
184 | =item $lh->init(); |
185 | |
186 | This is called by ->new to initialize newly-constructed language handles. |
187 | If you define an init method in your class, remember that it's usually |
188 | considered a good idea to call $lh->SUPER::init in it (presumably at the |
189 | beginning), so that all classes get a chance to initialize a new object |
190 | however they see fit. |
191 | |
192 | =item YourProjClass->fallback_languages() |
193 | |
194 | C<get_handle> appends the return value of this to the end of |
195 | whatever list of languages you pass C<get_handle>. Unless |
196 | you override this method, your project class |
197 | will inherit Locale::Maketext's C<fallback_languages>, which |
198 | currently returns C<('i-default', 'en', 'en-US')>. |
199 | ("i-default" is defined in RFC 2277). |
200 | |
201 | This method (by having it return the name |
202 | of a language-tag that has an existing language class) |
203 | can be used for making sure that |
204 | C<get_handle> will always manage to construct a language |
205 | handle (assuming your language classes are in an appropriate |
206 | @INC directory). Or you can use the next method: |
207 | |
208 | =item YourProjClass->fallback_language_classes() |
209 | |
210 | C<get_handle> appends the return value of this to the end |
211 | of the list of classes it will try using. Unless |
212 | you override this method, your project class |
213 | will inherit Locale::Maketext's C<fallback_language_classes>, |
214 | which currently returns an empty list, C<()>. |
215 | By setting this to some value (namely, the name of a loadable |
216 | language class), you can be sure that |
217 | C<get_handle> will always manage to construct a language |
218 | handle. |
219 | |
220 | =back |
221 | |
222 | =head2 The "maketext" Method |
223 | |
224 | This is the most important method in Locale::Maketext: |
225 | |
226 | $text = $lh->maketext(I<key>, ...parameters for this phrase...); |
227 | |
228 | This looks in the %Lexicon of the language handle |
229 | $lh and all its superclasses, looking |
230 | for an entry whose key is the string I<key>. Assuming such |
231 | an entry is found, various things then happen, depending on the |
232 | value found: |
233 | |
234 | If the value is a scalarref, the scalar is dereferenced and returned |
235 | (and any parameters are ignored). |
236 | If the value is a coderef, we return &$value($lh, ...parameters...). |
237 | If the value is a string that I<doesn't> look like it's in Bracket Notation, |
238 | we return it (after replacing it with a scalarref, in its %Lexicon). |
239 | If the value I<does> look like it's in Bracket Notation, then we compile |
240 | it into a sub, replace the string in the %Lexicon with the new coderef, |
241 | and then we return &$new_sub($lh, ...parameters...). |
242 | |
243 | Bracket Notation is discussed in a later section. Note |
244 | that trying to compile a string into Bracket Notation can throw |
245 | an exception if the string is not syntactically valid (say, by not |
246 | balancing brackets right.) |
247 | |
248 | Also, calling &$coderef($lh, ...parameters...) can throw any sort of |
249 | exception (if, say, code in that sub tries to divide by zero). But |
250 | a very common exception occurs when you have Bracket |
251 | Notation text that says to call a method "foo", but there is no such |
252 | method. (E.g., "You have [quaB<tn>,_1,ball]." will throw an exception |
253 | on trying to call $lh->quaB<tn>($_[1],'ball') -- you presumably meant |
254 | "quant".) C<maketext> catches these exceptions, but only to make the |
255 | error message more readable, at which point it rethrows the exception. |
256 | |
257 | An exception I<may> be thrown if I<key> is not found in any |
258 | of $lh's %Lexicon hashes. What happens if a key is not found, |
259 | is discussed in a later section, "Controlling Lookup Failure". |
260 | |
261 | Note that you might find it useful in some cases to override |
262 | the C<maketext> method with an "after method", if you want to |
263 | translate encodings, or even scripts: |
264 | |
265 | package YrProj::zh_cn; # Chinese with PRC-style glyphs |
266 | use base ('YrProj::zh_tw'); # Taiwan-style |
267 | sub maketext { |
268 | my $self = shift(@_); |
269 | my $value = $self->maketext(@_); |
270 | return Chineeze::taiwan2mainland($value); |
271 | } |
272 | |
273 | Or you may want to override it with something that traps |
274 | any exceptions, if that's critical to your program: |
275 | |
276 | sub maketext { |
277 | my($lh, @stuff) = @_; |
278 | my $out; |
279 | eval { $out = $lh->SUPER::maketext(@stuff) }; |
280 | return $out unless $@; |
281 | ...otherwise deal with the exception... |
282 | } |
283 | |
284 | Other than those two situations, I don't imagine that |
285 | it's useful to override the C<maketext> method. (If |
286 | you run into a situation where it is useful, I'd be |
287 | interested in hearing about it.) |
288 | |
289 | =over |
290 | |
291 | =item $lh->fail_with I<or> $lh->fail_with(I<PARAM>) |
292 | |
293 | =item $lh->failure_handler_auto |
294 | |
295 | These two methods are discussed in the section "Controlling |
296 | Lookup Failure". |
297 | |
298 | =back |
299 | |
300 | =head2 Utility Methods |
301 | |
302 | These are methods that you may find it handy to use, generally |
303 | from %Lexicon routines of yours (whether expressed as |
304 | Bracket Notation or not). |
305 | |
306 | =over |
307 | |
308 | =item $language->quant($number, $singular) |
309 | |
310 | =item $language->quant($number, $singular, $plural) |
311 | |
312 | =item $language->quant($number, $singular, $plural, $negative) |
313 | |
314 | This is generally meant to be called from inside Bracket Notation |
315 | (which is discussed later), as in |
316 | |
317 | "Your search matched [quant,_1,document]!" |
318 | |
319 | It's for I<quantifying> a noun (i.e., saying how much of it there is, |
320 | while giving the currect form of it). The behavior of this method is |
321 | handy for English and a few other Western European languages, and you |
322 | should override it for languages where it's not suitable. You can feel |
323 | free to read the source, but the current implementation is basically |
324 | as this pseudocode describes: |
325 | |
326 | if $number is 0 and there's a $negative, |
327 | return $negative; |
328 | elsif $number is 1, |
329 | return "1 $singular"; |
330 | elsif there's a $plural, |
331 | return "$number $plural"; |
332 | else |
333 | return "$number " . $singular . "s"; |
334 | # |
335 | # ...except that we actually call numf to |
336 | # stringify $number before returning it. |
337 | |
338 | So for English (with Bracket Notation) |
339 | C<"...[quant,_1,file]..."> is fine (for 0 it returns "0 files", |
340 | for 1 it returns "1 file", and for more it returns "2 files", etc.) |
341 | |
342 | But for "directory", you'd want C<"[quant,_1,direcory,directories]"> |
343 | so that our elementary C<quant> method doesn't think that the |
344 | plural of "directory" is "directorys". And you might find that the |
345 | output may sound better if you specify a negative form, as in: |
346 | |
347 | "[quant,_1,file,files,No files] matched your query.\n" |
348 | |
349 | Remember to keep in mind verb agreement (or adjectives too, in |
350 | other languages), as in: |
351 | |
352 | "[quant,_1,document] were matched.\n" |
353 | |
354 | Because if _1 is one, you get "1 document B<were> matched". |
355 | An acceptable hack here is to do something like this: |
356 | |
357 | "[quant,_1,document was, documents were] matched.\n" |
358 | |
359 | =item $language->numf($number) |
360 | |
361 | This returns the given number formatted nicely according to |
362 | this language's conventions. Maketext's default method is |
363 | mostly to just take the normal string form of the number |
364 | (applying sprintf "%G" for only very large numbers), and then |
365 | to add commas as necessary. (Except that |
366 | we apply C<tr/,./.,/> if $language->{'numf_comma'} is true; |
367 | that's a bit of a hack that's useful for languages that express |
368 | two million as "2.000.000" and not as "2,000,000"). |
369 | |
370 | If you want anything fancier, consider overriding this with something |
371 | that uses L<Number::Format|Number::Format>, or does something else |
372 | entirely. |
373 | |
374 | Note that numf is called by quant for stringifying all quantifying |
375 | numbers. |
376 | |
377 | =item $language->sprintf($format, @items) |
378 | |
379 | This is just a wrapper around Perl's normal C<sprintf> function. |
380 | It's provided so that you can use "sprintf" in Bracket Notation: |
381 | |
382 | "Couldn't access datanode [sprintf,%10x=~[%s~],_1,_2]!\n" |
383 | |
384 | returning... |
385 | |
386 | Couldn't access datanode Stuff=[thangamabob]! |
387 | |
388 | =item $language->language_tag() |
389 | |
390 | Currently this just takes the last bit of C<ref($language)>, turns |
391 | underscores to dashes, and returns it. So if $language is |
392 | an object of class Hee::HOO::Haw::en_us, $language->language_tag() |
393 | returns "en-us". (Yes, the usual representation for that language |
394 | tag is "en-US", but case is I<never> considered meaningful in |
395 | language-tag comparison.) |
396 | |
397 | You may override this as you like; Maketext doesn't use it for |
398 | anything. |
399 | |
400 | =item $language->encoding() |
401 | |
402 | Currently this isn't used for anything, but it's provided |
403 | (with default value of |
404 | C<(ref($language) && $language-E<gt>{'encoding'})) or "iso-8859-1"> |
405 | ) as a sort of suggestion that it may be useful/necessary to |
406 | associate encodings with your language handles (whether on a |
407 | per-class or even per-handle basis.) |
408 | |
409 | =back |
410 | |
411 | =head2 Language Handle Attributes and Internals |
412 | |
413 | A language handle is a flyweight object -- i.e., it doesn't (necessarily) |
414 | carry any data of interest, other than just being a member of |
415 | whatever class it belongs to. |
416 | |
417 | A language handle is implemented as a blessed hash. Subclasses of yours |
418 | can store whatever data you want in the hash. Currently the only hash |
419 | entry used by any crucial Maketext method is "fail", so feel free to |
420 | use anything else as you like. |
421 | |
422 | B<Remember: Don't be afraid to read the Maketext source if there's |
423 | any point on which this documentation is unclear.> This documentation |
424 | is vastly longer than the module source itself. |
425 | |
426 | =over |
427 | |
428 | =back |
429 | |
430 | =head1 LANGUAGE CLASS HIERARCHIES |
431 | |
432 | These are Locale::Maketext's assumptions about the class |
433 | hierarchy formed by all your language classes: |
434 | |
435 | =over |
436 | |
437 | =item * |
438 | |
439 | You must have a project base class, which you load, and |
440 | which you then use as the first argument in |
441 | the call to YourProjClass->get_handle(...). It should derive |
442 | (whether directly or indirectly) from Locale::Maketext. |
443 | It B<doesn't matter> how you name this class, altho assuming this |
444 | is the localization component of your Super Mega Program, |
445 | good names for your project class might be |
446 | SuperMegaProgram::Localization, SuperMegaProgram::L10N, |
447 | SuperMegaProgram::I18N, SuperMegaProgram::International, |
448 | or even SuperMegaProgram::Languages or SuperMegaProgram::Messages. |
449 | |
450 | =item * |
451 | |
452 | Language classes are what YourProjClass->get_handle will try to load. |
453 | It will look for them by taking each language-tag (B<skipping> it |
454 | if it doesn't look like a language-tag or locale-tag!), turning it to |
455 | all lowercase, turning and dashes to underscores, and appending it |
456 | to YourProjClass . "::". So this: |
457 | |
458 | $lh = YourProjClass->get_handle( |
459 | 'en-US', 'fr', 'kon', 'i-klingon', 'i-klingon-romanized' |
460 | ); |
461 | |
462 | will try loading the classes |
463 | YourProjClass::en_us (note lowercase!), YourProjClass::fr, |
464 | YourProjClass::kon, |
465 | YourProjClass::i_klingon |
466 | and YourProjClass::i_klingon_romanized. (And it'll stop at the |
467 | first one that actually loads.) |
468 | |
469 | =item * |
470 | |
471 | I assume that each language class derives (directly or indirectly) |
472 | from your project class, and also defines its @ISA, its %Lexicon, |
473 | or both. But I anticipate no dire consequences if these assumptions |
474 | do not hold. |
475 | |
476 | =item * |
477 | |
478 | Language classes may derive from other language classes (altho they |
479 | should have "use I<Thatclassname>" or "use base qw(I<...classes...>)"). |
480 | They may derive from the project |
481 | class. They may derive from some other class altogether. Or via |
482 | multiple inheritance, it may derive from any mixture of these. |
483 | |
484 | =item * |
485 | |
486 | I foresee no problems with having multiple inheritance in |
487 | your hierarchy of language classes. (As usual, however, Perl will |
488 | complain bitterly if you have a cycle in the hierarchy: i.e., if |
489 | any class is its own ancestor.) |
490 | |
491 | =back |
492 | |
493 | =head1 ENTRIES IN EACH LEXICON |
494 | |
495 | A typical %Lexicon entry is meant to signify a phrase, |
496 | taking some number (0 or more) of parameters. An entry |
497 | is meant to be accessed by via |
498 | a string I<key> in $lh->maketext(I<key>, ...parameters...), |
499 | which should return a string that is generally meant for |
500 | be used for "output" to the user -- regardless of whether |
501 | this actually means printing to STDOUT, writing to a file, |
502 | or putting into a GUI widget. |
503 | |
504 | While the key must be a string value (since that's a basic |
505 | restriction that Perl places on hash keys), the value in |
506 | the lexicon can currenly be of several types: |
507 | a defined scalar, scalarref, or coderef. The use of these is |
508 | explained above, in the section 'The "maketext" Method', and |
509 | Bracket Notation for strings is discussed in the next section. |
510 | |
511 | While you can use arbitrary unique IDs for lexicon keys |
512 | (like "_min_larger_max_error"), it is often |
513 | useful for if an entry's key is itself a valid value, like |
514 | this example error message: |
515 | |
516 | "Minimum ([_1]) is larger than maximum ([_2])!\n", |
517 | |
518 | Compare this code that uses an arbitrary ID... |
519 | |
520 | die $lh->maketext( "_min_larger_max_error", $min, $max ) |
521 | if $min > $max; |
522 | |
523 | ...to this code that uses a key-as-value: |
524 | |
525 | die $lh->maketext( |
526 | "Minimum ([_1]) is larger than maximum ([_2])!\n", |
527 | $min, $max |
528 | ) if $min > $max; |
529 | |
530 | The second is, in short, more readable. In particular, it's obvious |
531 | that the number of parameters you're feeding to that phrase (two) is |
532 | the number of parameters that it I<wants> to be fed. (Since you see |
533 | _1 and a _2 being used in the key there.) |
534 | |
535 | Also, once a project is otherwise |
536 | complete and you start to localize it, you can scrape together |
537 | all the various keys you use, and pass it to a translator; and then |
538 | the translator's work will go faster if what he's presented is this: |
539 | |
540 | "Minimum ([_1]) is larger than maximum ([_2])!\n", |
541 | => "", # fill in something here, Jacques! |
542 | |
543 | rather than this more cryptic mess: |
544 | |
545 | "_min_larger_max_error" |
546 | => "", # fill in something here, Jacques |
547 | |
548 | I think that keys as lexicon values makes the completed lexicon |
549 | entries more readable: |
550 | |
551 | "Minimum ([_1]) is larger than maximum ([_2])!\n", |
552 | => "Le minimum ([_1]) est plus grand que le maximum ([_2])!\n", |
553 | |
554 | Also, having valid values as keys becomes very useful if you set |
555 | up an _AUTO lexicon. _AUTO lexicons are discussed in a later |
556 | section. |
557 | |
558 | I almost always use keys that are themselves |
559 | valid lexicon values. One notable exception is when the value is |
560 | quite long. For example, to get the screenful of data that |
561 | a command-line program might returns when given an unknown switch, |
562 | I often just use a key "_USAGE_MESSAGE". At that point I then go |
563 | and immediately to define that lexicon entry in the |
564 | ProjectClass::L10N::en lexicon (since English is always my "project |
565 | lanuage"): |
566 | |
567 | '_USAGE_MESSAGE' => <<'EOSTUFF', |
568 | ...long long message... |
569 | EOSTUFF |
570 | |
571 | and then I can use it as: |
572 | |
573 | getopt('oDI', \%opts) or die $lh->maketext('_USAGE_MESSAGE'); |
574 | |
575 | Incidentally, |
576 | note that each class's C<%Lexicon> inherits-and-extends |
577 | the lexicons in its superclasses. This is not because these are |
578 | special hashes I<per se>, but because you access them via the |
579 | C<maketext> method, which looks for entries across all the |
580 | C<%Lexicon>'s in a language class I<and> all its ancestor classes. |
581 | (This is because the idea of "class data" isn't directly implemented |
582 | in Perl, but is instead left to individual class-systems to implement |
583 | as they see fit..) |
584 | |
585 | Note that you may have things stored in a lexicon |
586 | besides just phrases for output: for example, if your program |
587 | takes input from the keyboard, asking a "(Y/N)" question, |
588 | you probably need to know what equivalent of "Y[es]/N[o]" is |
589 | in whatever language. You probably also need to know what |
590 | the equivalents of the answers "y" and "n" are. You can |
591 | store that information in the lexicon (say, under the keys |
592 | "~answer_y" and "~answer_n", and the long forms as |
593 | "~answer_yes" and "~answer_no", where "~" is just an ad-hoc |
594 | character meant to indicate to programmers/translators that |
595 | these are not phrases for output). |
596 | |
597 | Or instead of storing this in the language class's lexicon, |
598 | you can (and, in some cases, really should) represent the same bit |
599 | of knowledge as code is a method in the language class. (That |
600 | leaves a tidy distinction between the lexicon as the things we |
601 | know how to I<say>, and the rest of the things in the lexicon class |
602 | as things that we know how to I<do>.) Consider |
603 | this example of a processor for responses to French "oui/non" |
604 | questions: |
605 | |
606 | sub y_or_n { |
607 | return undef unless defined $_[1] and length $_[1]; |
608 | my $answer = lc $_[1]; # smash case |
609 | return 1 if $answer eq 'o' or $answer eq 'oui'; |
610 | return 0 if $answer eq 'n' or $answer eq 'non'; |
611 | return undef; |
612 | } |
613 | |
614 | ...which you'd then call in a construct like this: |
615 | |
616 | my $response; |
617 | until(defined $response) { |
618 | print $lh->maketext("Open the pod bay door (y/n)? "); |
619 | $response = $lh->y_or_n( get_input_from_keyboard_somehow() ); |
620 | } |
621 | if($response) { $pod_bay_door->open() } |
622 | else { $pod_bay_door->leave_closed() } |
623 | |
624 | Other data worth storing in a lexicon might be things like |
625 | filenames for language-targetted resources: |
626 | |
627 | ... |
628 | "_main_splash_png" |
629 | => "/styles/en_us/main_splash.png", |
630 | "_main_splash_imagemap" |
631 | => "/styles/en_us/main_splash.incl", |
632 | "_general_graphics_path" |
633 | => "/styles/en_us/", |
634 | "_alert_sound" |
635 | => "/styles/en_us/hey_there.wav", |
636 | "_forward_icon" |
637 | => "left_arrow.png", |
638 | "_backward_icon" |
639 | => "right_arrow.png", |
640 | # In some other languages, left equals |
641 | # BACKwards, and right is FOREwards. |
642 | ... |
643 | |
644 | You might want to do the same thing for expressing key bindings |
645 | or the like (since hardwiring "q" as the binding for the function |
646 | that quits a screen/menu/program is useful only if your language |
647 | happens to associate "q" with "quit"!) |
648 | |
649 | =head1 BRACKET NOTATION |
650 | |
651 | Bracket Notation is a crucial feature of Locale::Maketext. I mean |
652 | Bracket Notation to provide a replacement for sprintf formatting. |
653 | Everything you do with Bracket Notation could be done with a sub block, |
654 | but bracket notation is meant to be much more concise. |
655 | |
656 | Bracket Notation is a like a miniature "template" system (in the sense |
657 | of L<Text::Template|Text::Template>, not in the sense of C++ templates), |
658 | where normal text is passed thru basically as is, but text is special |
659 | regions is specially interpreted. In Bracket Notation, you use brackets |
660 | ("[...]" -- not "{...}"!) to note sections that are specially interpreted. |
661 | |
662 | For example, here all the areas that are taken literally are underlined with |
663 | a "^", and all the in-bracket special regions are underlined with an X: |
664 | |
665 | "Minimum ([_1]) is larger than maximum ([_2])!\n", |
666 | ^^^^^^^^^ XX ^^^^^^^^^^^^^^^^^^^^^^^^^^ XX ^^^^ |
667 | |
668 | When that string is compiled from bracket notation into a real Perl sub, |
669 | it's basically turned into: |
670 | |
671 | sub { |
672 | my $lh = $_[0]; |
673 | my @params = @_; |
674 | return join '', |
675 | "Minimum (", |
676 | ...some code here... |
677 | ") is larger than maximum (", |
678 | ...some code here... |
679 | ")!\n", |
680 | } |
681 | # to be called by $lh->maketext(KEY, params...) |
682 | |
683 | In other words, text outside bracket groups is turned into string |
684 | literals. Text in brackets is rather more complex, and currently follows |
685 | these rules: |
686 | |
687 | =over |
688 | |
689 | =item * |
690 | |
691 | Bracket groups that are empty, or which consist only of whitespace, |
692 | are ignored. (Examples: "[]", "[ ]", or a [ and a ] with returns |
693 | and/or tabs and/or spaces between them. |
694 | |
695 | Otherwise, each group is taken to be a comma-separated group of items, |
696 | and each item is interpreted as follows: |
697 | |
698 | =item * |
699 | |
700 | An item that is "_I<digits>" or "_-I<digits>" is interpreted as |
701 | $_[I<value>]. I.e., "_1" is becomes with $_[1], and "_-3" is interpreted |
702 | as $_[-3] (in which case @_ should have at least three elements in it). |
703 | Note that $_[0] is the language handle, and is typically not named |
704 | directly. |
705 | |
706 | =item * |
707 | |
708 | An item "_*" is interpreted to mean "all of @_ except $_[0]". |
709 | I.e., C<@_[1..$#_]>. Note that this is an empty list in the case |
710 | of calls like $lh->maketext(I<key>) where there are no |
711 | parameters (except $_[0], the language handle). |
712 | |
713 | =item * |
714 | |
715 | Otherwise, each item is interpreted as a string literal. |
716 | |
717 | =back |
718 | |
719 | The group as a whole is interpreted as follows: |
720 | |
721 | =over |
722 | |
723 | =item * |
724 | |
725 | If the first item in a bracket group looks like a method name, |
726 | then that group is interpreted like this: |
727 | |
728 | $lh->that_method_name( |
729 | ...rest of items in this group... |
730 | ), |
731 | |
732 | =item * |
733 | |
734 | If the first item in a bracket group is empty-string, or "_*" |
735 | or "_I<digits>" or "_-I<digits>", then that group is interpreted |
736 | as just the interpolation of all its items: |
737 | |
738 | join('', |
739 | ...rest of items in this group... |
740 | ), |
741 | |
742 | Examples: "[_1]" and "[,_1]", which are synonymous; and |
743 | "[,ID-(,_4,-,_2,)]", which compiles as |
744 | C<join "", "ID-(", $_[4], "-", $_[2], ")">. |
745 | |
746 | =item * |
747 | |
748 | Otherwise this bracket group is invalid. For example, in the group |
749 | "[!@#,whatever]", the first item C<"!@#"> is neither empty-string, |
750 | "_I<number>", "_-I<number>", "_*", nor a valid method name; and so |
751 | Locale::Maketext will throw an exception of you try compiling an |
752 | expression containing this bracket group. |
753 | |
754 | =back |
755 | |
756 | Note, incidentally, that items in each group are comma-separated, |
757 | not C</\s*,\s*/>-separated. That is, you might expect that this |
758 | bracket group: |
759 | |
760 | "Hoohah [foo, _1 , bar ,baz]!" |
761 | |
762 | would compile to this: |
763 | |
764 | sub { |
765 | my $lh = $_[0]; |
766 | return join '', |
767 | "Hoohah ", |
768 | $lh->foo( $_[1], "bar", "baz"), |
769 | "!", |
770 | } |
771 | |
772 | But it actually compiles as this: |
773 | |
774 | sub { |
775 | my $lh = $_[0]; |
776 | return join '', |
777 | "Hoohah ", |
778 | $lh->foo(" _1 ", " bar ", "baz"), #!!! |
779 | "!", |
780 | } |
781 | |
782 | In the notation discussed so far, the characters "[" and "]" are given |
783 | special meaning, for opening and closing bracket groups, and "," has |
784 | a special meaning inside bracket groups, where it separates items in the |
785 | group. This begs the question of how you'd express a literal "[" or |
786 | "]" in a Bracket Notation string, and how you'd express a literal |
787 | comma inside a bracket group. For this purpose I've adopted "~" (tilde) |
788 | as an escape character: "~[" means a literal '[' character anywhere |
789 | in Bracket Notation (i.e., regardless of whether you're in a bracket |
790 | group or not), and ditto for "~]" meaning a literal ']', and "~," meaning |
791 | a literal comma. (Altho "," means a literal comma outside of |
792 | bracket groups -- it's only inside bracket groups that commas are special.) |
793 | |
794 | And on the off chance you need a literal tilde in a bracket expression, |
795 | you get it with "~~". |
796 | |
797 | Currently, an unescaped "~" before a character |
798 | other than a bracket or a comma is taken to mean just a "~" and that |
799 | charecter. I.e., "~X" means the same as "~~X" -- i.e., one literal tilde, |
800 | and then one literal "X". However, by using "~X", you are assuming that |
801 | no future version of Maketext will use "~X" as a magic escape sequence. |
802 | In practice this is not a great problem, since first off you can just |
803 | write "~~X" and not worry about it; second off, I doubt I'll add lots |
804 | of new magic characters to bracket notation; and third off, you |
805 | aren't likely to want literal "~" characters in your messages anyway, |
806 | since it's not a character with wide use in natural language text. |
807 | |
808 | Brackets must be balanced -- every openbracket must have |
809 | one matching closebracket, and vice versa. So these are all B<invalid>: |
810 | |
811 | "I ate [quant,_1,rhubarb pie." |
812 | "I ate [quant,_1,rhubarb pie[." |
813 | "I ate quant,_1,rhubarb pie]." |
814 | "I ate quant,_1,rhubarb pie[." |
815 | |
816 | Currently, bracket groups do not nest. That is, you B<cannot> say: |
817 | |
818 | "Foo [bar,baz,[quux,quuux]]\n"; |
819 | |
820 | If you need a notation that's that powerful, use normal Perl: |
821 | |
822 | %Lexicon = ( |
823 | ... |
824 | "some_key" => sub { |
825 | my $lh = $_[0]; |
826 | join '', |
827 | "Foo ", |
828 | $lh->bar('baz', $lh->quux('quuux')), |
829 | "\n", |
830 | }, |
831 | ... |
832 | ); |
833 | |
834 | Or write the "bar" method so you don't need to pass it the |
835 | output from calling quux. |
836 | |
837 | I do not anticipate that you will need (or particularly want) |
838 | to nest bracket groups, but you are welcome to email me with |
839 | convincing (real-life) arguments to the contrary. |
840 | |
841 | =head1 AUTO LEXICONS |
842 | |
843 | If maketext goes to look in an individual %Lexicon for an entry |
844 | for I<key> (where I<key> does not start with an underscore), and |
845 | sees none, B<but does see> an entry of "_AUTO" => I<some_true_value>, |
846 | then we actually define $Lexicon{I<key>} = I<key> right then and there, |
847 | and then use that value as if it had been there all |
848 | along. This happens before we even look in any superclass %Lexicons! |
849 | |
850 | (This is meant to be somewhat like the AUTOLOAD mechanism in |
851 | Perl's function call system -- or, looked at another way, |
852 | like the L<AutoLoader|AutoLoader> module.) |
853 | |
854 | I can picture all sorts of circumstances where you just |
855 | do not want lookup to be able to fail (since failing |
856 | normally means that maketext throws a C<die>, altho |
857 | see the next section for greater control over that). But |
858 | here's one circumstance where _AUTO lexicons are meant to |
859 | be I<especially> useful: |
860 | |
861 | As you're writing an application, you decide as you go what messages |
862 | you need to emit. Normally you'd go to write this: |
863 | |
864 | if(-e $filename) { |
865 | go_process_file($filename) |
866 | } else { |
867 | print "Couldn't find file \"$filename\"!\n"; |
868 | } |
869 | |
870 | but since you anticipate localizing this, you write: |
871 | |
872 | use ThisProject::I18N; |
873 | my $lh = ThisProject::I18N->get_handle(); |
874 | # For the moment, assume that things are set up so |
875 | # that we load class ThisProject::I18N::en |
876 | # and that that's the class that $lh belongs to. |
877 | ... |
878 | if(-e $filename) { |
879 | go_process_file($filename) |
880 | } else { |
881 | print $lh->maketext( |
882 | "Couldn't find file \"[_1]\"!\n", $filename |
883 | ); |
884 | } |
885 | |
886 | Now, right after you've just written the above lines, you'd |
887 | normally have to go open the file |
888 | ThisProject/I18N/en.pm, and immediately add an entry: |
889 | |
890 | "Couldn't find file \"[_1]\"!\n" |
891 | => "Couldn't find file \"[_1]\"!\n", |
892 | |
893 | But I consider that somewhat of a distraction from the work |
894 | of getting the main code working -- to say nothing of the fact |
895 | that I often have to play with the program a few times before |
896 | I can decide exactly what wording I want in the messages (which |
897 | in this case would require me to go changing three lines of code: |
898 | the call to maketext with that key, and then the two lines in |
899 | ThisProject/I18N/en.pm). |
900 | |
901 | However, if you set "_AUTO => 1" in the %Lexicon in, |
902 | ThisProject/I18N/en.pm (assuming that English (en) is |
903 | the language that all your programmers will be using for this |
904 | project's internal message keys), then you don't ever have to |
905 | go adding lines like this |
906 | |
907 | "Couldn't find file \"[_1]\"!\n" |
908 | => "Couldn't find file \"[_1]\"!\n", |
909 | |
910 | to ThisProject/I18N/en.pm, because if _AUTO is true there, |
911 | then just looking for an entry with the key "Couldn't find |
912 | file \"[_1]\"!\n" in that lexicon will cause it to be added, |
913 | with that value! |
914 | |
915 | Note that the reason that keys that start with "_" |
916 | are immune to _AUTO isn't anything generally magical about |
917 | the underscore character -- I just wanted a way to have most |
918 | lexicon keys be autoable, except for possibly a few, and I |
919 | arbitrarily decided to use a leading underscore as a signal |
920 | to distinguish those few. |
921 | |
922 | =head1 CONTROLLING LOOKUP FAILURE |
923 | |
924 | If you call $lh->maketext(I<key>, ...parameters...), |
925 | and there's no entry I<key> in $lh's class's %Lexicon, nor |
926 | in the superclass %Lexicon hash, I<and> if we can't auto-make |
927 | I<key> (because either it starts with a "_", or because none |
928 | of its lexicons have C<_AUTO =E<gt> 1,>), then we have |
929 | failed to find a normal way to maketext I<key>. What then |
930 | happens in these failure conditions, depends on the $lh object |
931 | "fail" attribute. |
932 | |
933 | If the language handle has no "fail" attribute, maketext |
934 | will simply throw an exception (i.e., it calls C<die>, mentioning |
935 | the I<key> whose lookup failed, and naming the line number where |
936 | the calling $lh->maketext(I<key>,...) was. |
937 | |
938 | If the language handle has a "fail" attribute whose value is a |
939 | coderef, then $lh->maketext(I<key>,...params...) gives up and calls: |
940 | |
941 | return &{$that_subref}($lh, $key, @params); |
942 | |
943 | Otherwise, the "fail" attribute's value should be a string denoting |
944 | a method name, so that $lh->maketext(I<key>,...params...) can |
945 | give up with: |
946 | |
947 | return $lh->$that_method_name($phrase, @params); |
948 | |
949 | The "fail" attribute can be accessed with the C<fail_with> method: |
950 | |
951 | # Set to a coderef: |
952 | $lh->fail_with( \&failure_handler ); |
953 | |
954 | # Set to a method name: |
955 | $lh->fail_with( 'failure_method' ); |
956 | |
957 | # Set to nothing (i.e., so failure throws a plain exception) |
958 | $lh->fail_with( undef ); |
959 | |
960 | # Simply read: |
961 | $handler = $lh->fail_with(); |
962 | |
963 | Now, as to what you may want to do with these handlers: Maybe you'd |
964 | want to log what key failed for what class, and then die. Maybe |
965 | you don't like C<die> and instead you want to send the error message |
966 | to STDOUT (or wherever) and then merely C<exit()>. |
967 | |
968 | Or maybe you don't want to C<die> at all! Maybe you could use a |
969 | handler like this: |
970 | |
971 | # Make all lookups fall back onto an English value, |
972 | # but after we log it for later fingerpointing. |
973 | my $lh_backup = ThisProject->get_handle('en'); |
974 | open(LEX_FAIL_LOG, ">>wherever/lex.log") || die "GNAARGH $!"; |
975 | sub lex_fail { |
976 | my($failing_lh, $key, $params) = @_; |
977 | print LEX_FAIL_LOG scalar(localtime), "\t", |
978 | ref($failing_lh), "\t", $key, "\n"; |
979 | return $lh_backup->maketext($key,@params); |
980 | } |
981 | |
982 | Some users have expressed that they think this whole mechanism of |
983 | having a "fail" attribute at all, seems a rather pointless complication. |
984 | But I want Locale::Maketext to be usable for software projects of I<any> |
985 | scale and type; and different software projects have different ideas |
986 | of what the right thing is to do in failure conditions. I could simply |
987 | say that failure always throws an exception, and that if you want to be |
988 | careful, you'll just have to wrap every call to $lh->maketext in an |
989 | S<eval { }>. However, I want programmers to reserve the right (via |
990 | the "fail" attribute) to treat lookup failure as something other than |
991 | an exception of the same level of severity as a config file being |
992 | unreadable, or some essential resource being inaccessable. |
993 | |
994 | One possibly useful value for the "fail" attribute is the method name |
995 | "failure_handler_auto". This is a method defined in class |
996 | Locale::Maketext itself. You set it with: |
997 | |
998 | $lh->fail_with('failure_handler_auto'); |
999 | |
1000 | Then when you call $lh->maketext(I<key>, ...parameters...) and |
1001 | there's no I<key> in any of those lexicons, maketext gives up with |
1002 | |
1003 | return $lh->failure_handler_auto($key, @params); |
1004 | |
1005 | But failure_handler_auto, instead of dying or anything, compiles |
1006 | $key, caching it in $lh->{'failure_lex'}{$key} = $complied, |
1007 | and then calls the compiled value, and returns that. (I.e., if |
1008 | $key looks like bracket notation, $compiled is a sub, and we return |
1009 | &{$compiled}(@params); but if $key is just a plain string, we just |
1010 | return that.) |
1011 | |
1012 | The effect of using "failure_auto_handler" |
1013 | is like an AUTO lexicon, except that it 1) compiles $key even if |
1014 | it starts with "_", and 2) you have a record in the new hashref |
1015 | $lh->{'failure_lex'} of all the keys that have failed for |
1016 | this object. This should avoid your program dying -- as long |
1017 | as your keys aren't actually invalid as bracket code, and as |
1018 | long as they don't try calling methods that don't exist. |
1019 | |
1020 | "failure_auto_handler" may not be exactly what you want, but I |
1021 | hope it at least shows you that maketext failure can be mitigated |
1022 | in any number of very flexible ways. If you can formalize exactly |
1023 | what you want, you should be able to express that as a failure |
1024 | handler. You can even make it default for every object of a given |
1025 | class, by setting it in that class's init: |
1026 | |
1027 | sub init { |
1028 | my $lh = $_[0]; # a newborn handle |
1029 | $lh->SUPER::init(); |
1030 | $lh->fail_with('my_clever_failure_handler'); |
1031 | return; |
1032 | } |
1033 | sub my_clever_failure_handler { |
1034 | ...you clever things here... |
1035 | } |
1036 | |
1037 | =head1 HOW TO USE MAKETEXT |
1038 | |
1039 | Here is a brief checklist on how to use Maketext to localize |
1040 | applications: |
1041 | |
1042 | =over |
1043 | |
1044 | =item * |
1045 | |
1046 | Decide what system you'll use for lexicon keys. If you insist, |
1047 | you can use opaque IDs (if you're nostalgic for C<catgets>), |
1048 | but I have better suggestions in the |
1049 | section "Entries in Each Lexicon", above. Assuming you opt for |
1050 | meaningful keys that double as values (like "Minimum ([_1]) is |
1051 | larger than maximum ([_2])!\n"), you'll have to settle on what |
1052 | language those should be in. For the sake of argument, I'll |
1053 | call this English, specifically American English, "en-US". |
1054 | |
1055 | =item * |
1056 | |
1057 | Create a class for your localization project. This is |
1058 | the name of the class that you'll use in the idiom: |
1059 | |
1060 | use Projname::L10N; |
1061 | my $lh = Projname::L10N->get_handle(...) || die "Language?"; |
1062 | |
1063 | Assuming your call your class Projname::L10N, create a class |
1064 | consisting minimally of: |
1065 | |
1066 | package Projname::L10N; |
1067 | use base qw(Locale::Maketext); |
1068 | ...any methods you might want all your languages to share... |
1069 | |
1070 | # And, assuming you want the base class to be an _AUTO lexicon, |
1071 | # as is discussed a few sections up: |
1072 | |
1073 | 1; |
1074 | |
1075 | =item * |
1076 | |
1077 | Create a class for the language your internal keys are in. Name |
1078 | the class after the language-tag for that language, in lowercase, |
1079 | with dashes changed to underscores. Assuming your project's first |
1080 | language is US English, you should call this Projname::L10N::en_us. |
1081 | It should consist minimally of: |
1082 | |
1083 | package Projname::L10N::en_us; |
1084 | use base qw(Projname::L10N); |
1085 | %Lexicon = ( |
1086 | '_AUTO' => 1, |
1087 | ); |
1088 | 1; |
1089 | |
1090 | (For the rest of this section, I'll assume that this "first |
1091 | language class" of Projname::L10N::en_us has |
1092 | _AUTO lexicon.) |
1093 | |
1094 | =item * |
1095 | |
1096 | Go and write your program. Everywhere in your program where |
1097 | you would say: |
1098 | |
1099 | print "Foobar $thing stuff\n"; |
1100 | |
1101 | instead do it thru maketext, using no variable interpolation in |
1102 | the key: |
1103 | |
1104 | print $lh->maketext("Foobar [_1] stuff\n", $thing); |
1105 | |
1106 | If you get tired of constantly saying C<print $lh-E<gt>maketext>, |
1107 | consider making a functional wrapper for it, like so: |
1108 | |
1109 | use Projname::L10N; |
1110 | use vars qw($lh); |
1111 | $lh = Projname::L10N->get_handle(...) || die "Language?"; |
1112 | sub pmt (@) { print( $lh->maketext(@_)) } |
1113 | # "pmt" is short for "Print MakeText" |
1114 | $Carp::Verbose = 1; |
1115 | # so if maketext fails, we see made the call to pmt |
1116 | |
1117 | Besides whole phrases meant for output, anything language-dependent |
1118 | should be put into the class Projname::L10N::en_us, |
1119 | whether as methods, or as lexicon entries -- this is discussed |
1120 | in the section "Entries in Each Lexicon", above. |
1121 | |
1122 | =item * |
1123 | |
1124 | Once the program is otherwise done, and once its localization for |
1125 | the first language works right (via the data and methods in |
1126 | Projname::L10N::en_us), you can get together the data for translation. |
1127 | If your first language lexicon isn't an _AUTO lexicon, then you already |
1128 | have all the messages explicitly in the lexicon (or else you'd be |
1129 | getting exceptions thrown when you call $lh->maketext to get |
1130 | messages that aren't in there). But if you were (advisedly) lazy and are |
1131 | using an _AUTO lexicon, then you've got to make a list of all the phrases |
1132 | that you've so far been letting _AUTO generate for you. There are very |
1133 | many ways to assemble such a list. The most straightforward is to simply |
1134 | grep the source for every occurrence of "maketext" (or calls |
1135 | to wrappers around it, like the above C<pmt> function), and to log the |
1136 | following phrase. |
1137 | |
1138 | =item * |
1139 | |
1140 | You may at this point want to consider whether the your base class |
1141 | (Projname::L10N) that all lexicons inherit from (Projname::L10N::en, |
1142 | Projname::L10N::es, etc.) should be an _AUTO lexicon. It may be true |
1143 | that in theory, all needed messages will be in each language class; |
1144 | but in the presumably unlikely or "impossible" case of lookup failure, |
1145 | you should consider whether your program should throw an exception, |
1146 | emit text in English (or whatever your project's first language is), |
1147 | or some more complex solution as described in the section |
1148 | "Controlling Lookup Failure", above. |
1149 | |
1150 | =item * |
1151 | |
1152 | Submit all messages/phrases/etc. to translators. |
1153 | |
1154 | (You may, in fact, want to start with localizing to I<one> other language |
1155 | at first, if you're not sure that you've property abstracted the |
1156 | language-dependent parts of your code.) |
1157 | |
1158 | Translators may request clarification of the situation in which a |
1159 | particular phrase is found. For example, in English we are entirely happy |
1160 | saying "I<n> files found", regardless of whether we mean "I looked for files, |
1161 | and found I<n> of them" or the rather distinct situation of "I looked for |
1162 | something else (like lines in files), and along the way I saw I<n> |
1163 | files." This may involve rethinking things that you thought quite clear: |
1164 | should "Edit" on a toolbar be a noun ("editing") or a verb ("to edit")? Is |
1165 | there already a conventionalized way to express that menu option, separate |
1166 | from the target language's normal word for "to edit"? |
1167 | |
1168 | In all cases where the very common phenomenon of quantification |
1169 | (saying "I<N> files", for B<any> value of N) |
1170 | is involved, each translator should make clear what dependencies the |
1171 | number causes in the sentence. In many cases, dependency is |
1172 | limited to words adjacent to the number, in places where you might |
1173 | expect them ("I found the-?PLURAL I<N> |
1174 | empty-?PLURAL directory-?PLURAL"), but in some cases there are |
1175 | unexpected dependencies ("I found-?PLURAL ..."!) as well as long-distance |
1176 | dependencies "The I<N> directory-?PLURAL could not be deleted-?PLURAL"!). |
1177 | |
1178 | Remind the translators to consider the case where N is 0: |
1179 | "0 files found" isn't exactly natural-sounding in any language, but it |
1180 | may be unacceptable in many -- or it may condition special |
1181 | kinds of agreement (similar to English "I didN'T find ANY files"). |
1182 | |
1183 | Remember to ask your translators about numeral formatting in their |
1184 | language, so that you can override the C<numf> method as |
1185 | appropriate. Typical variables in number formatting are: what to |
1186 | use as a decimal point (comma? period?); what to use as a thousands |
1187 | separator (space? nonbreakinng space? comma? period? small |
1188 | middot? prime? apostrophe?); and even whether the so-called "thousands |
1189 | separator" is actually for every third digit -- I've heard reports of |
1190 | two hundred thousand being expressable as "2,00,000" for some Indian |
1191 | (Subcontinental) languages, besides the less surprising "S<200 000>", |
1192 | "200.000", "200,000", and "200'000". Also, using a set of numeral |
1193 | glyphs other than the usual ASCII "0"-"9" might be appreciated, as via |
1194 | C<tr/0-9/\x{0966}-\x{096F}/> for getting digits in Devanagari script |
1195 | (for Hindi, Konkani, others). |
1196 | |
1197 | The basic C<quant> method that Locale::Maketext provides should be |
1198 | good for many languages. For some languages, it might be useful |
1199 | to modify it (or its constituent C<numerate> method) |
1200 | to take a plural form in the two-argument call to C<quant> |
1201 | (as in "[quant,_1,files]") if |
1202 | it's all-around easier to infer the singular form from the plural, than |
1203 | to infer the plural form from the singular. |
1204 | |
1205 | But for other languages (as is discussed at length |
1206 | in L<Locale::Maketext::TPJ13|Locale::Maketext::TPJ13>), simple |
1207 | C<quant>/C<numerify> is not enough. For the particularly problematic |
1208 | Slavic languages, what you may need is a method which you provide |
1209 | with the number, the citation form of the noun to quantify, and |
1210 | the case and gender that the sentence's syntax projects onto that |
1211 | noun slot. The method would then be responsible for determining |
1212 | what grammatical number that numeral projects onto its noun phrase, |
1213 | and what case and gender it may override the normal case and gender |
1214 | with; and then it would look up the noun in a lexicon providing |
1215 | all needed inflected forms. |
1216 | |
1217 | =item * |
1218 | |
1219 | You may also wish to discuss with the translators the question of |
1220 | how to relate different subforms of the same language tag, |
1221 | considering how this reacts with C<get_handle>'s treatment of |
1222 | these. For example, if a user accepts interfaces in "en, fr", and |
1223 | you have interfaces available in "en-US" and "fr", what should |
1224 | they get? You may wish to resolve this by establishing that "en" |
1225 | and "en-US" are effectively synonymous, by having one class |
1226 | zero-derive from the other. |
1227 | |
1228 | For some languages this issue may never come up (Danish is rarely |
1229 | expressed as "da-DK", but instead is just "da"). And for other |
1230 | languages, the whole concept of a "generic" form may verge on |
1231 | being uselessly vague, particularly for interfaces involving voice |
1232 | media in forms of Arabic or Chinese. |
1233 | |
1234 | =item * |
1235 | |
1236 | Once you've localized your program/site/etc. for all desired |
1237 | languages, be sure to show the result (whether live, or via |
1238 | screenshots) to the translators. Once they approve, make every |
1239 | effort to have it then checked by at least one other speaker of |
1240 | that language. This holds true even when (or especially when) the |
1241 | translation is done by one of your own programmers. Some |
1242 | kinds of systems may be harder to find testers for than others, |
1243 | depending on the amount of domain-specific jargon and concepts |
1244 | involved -- it's easier to find people who can tell you whether |
1245 | they approve of your translation for "delete this message" in an |
1246 | email-via-Web interface, than to find people who can give you |
1247 | an informed opinion on your translation for "attribute value" |
1248 | in an XML query tool's interface. |
1249 | |
1250 | =back |
1251 | |
1252 | =head1 SEE ALSO |
1253 | |
1254 | I recommend reading all of these: |
1255 | |
1256 | L<Locale::Maketext::TPJ13|Locale::Maketext::TPJ13> -- my I<The Perl |
1257 | Journal> article about Maketext. It explains many important concepts |
1258 | underlying Locale::Maketext's design, and some insight into why |
1259 | Maketext is better than the plain old approach of just having |
1260 | message catalogs that are just databases of sprintf formats. |
1261 | |
1262 | L<File::Findgrep|File::Findgrep> is a sample application/module |
1263 | that uses Locale::Maketext to localize its messages. |
1264 | |
1265 | L<I18N::LangTags|I18N::LangTags>. |
1266 | |
1267 | L<Win32::Locale|Win32::Locale>. |
1268 | |
1269 | RFC 3066, I<Tags for the Identification of Languages>, |
1270 | as at http://sunsite.dk/RFC/rfc/rfc3066.html |
1271 | |
1272 | RFC 2277, I<IETF Policy on Character Sets and Languages> |
1273 | is at http://sunsite.dk/RFC/rfc/rfc2277.html -- much of it is |
1274 | just things of interest to protocol designers, but it explains |
1275 | some basic concepts, like the distinction between locales and |
1276 | language-tags. |
1277 | |
1278 | The manual for GNU C<gettext>. The gettext dist is available in |
1279 | C<ftp://prep.ai.mit.edu/pub/gnu/> -- get |
1280 | a recent gettext tarball and look in its "doc/" directory, there's |
1281 | an easily browsable HTML version in there. The |
1282 | gettext documentation asks lots of questions worth thinking |
1283 | about, even if some of their answers are sometimes wonky, |
1284 | particularly where they start talking about pluralization. |
1285 | |
1286 | The Locale/Maketext.pm source. Obverse that the module is much |
1287 | shorter than its documentation! |
1288 | |
1289 | =head1 COPYRIGHT AND DISCLAIMER |
1290 | |
1291 | Copyright (c) 1999-2001 Sean M. Burke. All rights reserved. |
1292 | |
1293 | This library is free software; you can redistribute it and/or modify |
1294 | it under the same terms as Perl itself. |
1295 | |
1296 | This program is distributed in the hope that it will be useful, but |
1297 | without any warranty; without even the implied warranty of |
1298 | merchantability or fitness for a particular purpose. |
1299 | |
1300 | =head1 AUTHOR |
1301 | |
1302 | Sean M. Burke C<sburke@cpan.org> |
1303 | |
1304 | =cut |
1305 | |
1306 | # Zing! |