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# This document contains text in Perl "POD" format. | |
# Use a POD viewer like perldoc or perlman to render it. | |
=head1 NAME | |
Locale::Maketext::TPJ13 -- article about software localization | |
=head1 SYNOPSIS | |
# This an article, not a module. | |
=head1 DESCRIPTION | |
The following article by Sean M. Burke and Jordan Lachler | |
first appeared in I<The Perl Journal> #13 | |
and is copyright 1999 The Perl Journal. It appears | |
courtesy of Jon Orwant and The Perl Journal. This document may be | |
distributed under the same terms as Perl itself. | |
=head1 Localization and Perl: gettext breaks, Maketext fixes | |
by Sean M. Burke and Jordan Lachler | |
This article points out cases where gettext (a common system for | |
localizing software interfaces -- i.e., making them work in the user's | |
language of choice) fails because of basic differences between human | |
languages. This article then describes Maketext, a new system capable | |
of correctly treating these differences. | |
=head2 A Localization Horror Story: It Could Happen To You | |
=over | |
"There are a number of languages spoken by human beings in this | |
world." | |
-- Harald Tveit Alvestrand, in RFC 1766, "Tags for the | |
Identification of Languages" | |
=back | |
Imagine that your task for the day is to localize a piece of software | |
-- and luckily for you, the only output the program emits is two | |
messages, like this: | |
I scanned 12 directories. | |
Your query matched 10 files in 4 directories. | |
So how hard could that be? You look at the code that | |
produces the first item, and it reads: | |
printf("I scanned %g directories.", | |
$directory_count); | |
You think about that, and realize that it doesn't even work right for | |
English, as it can produce this output: | |
I scanned 1 directories. | |
So you rewrite it to read: | |
printf("I scanned %g %s.", | |
$directory_count, | |
$directory_count == 1 ? | |
"directory" : "directories", | |
); | |
...which does the Right Thing. (In case you don't recall, "%g" is for | |
locale-specific number interpolation, and "%s" is for string | |
interpolation.) | |
But you still have to localize it for all the languages you're | |
producing this software for, so you pull Locale::gettext off of CPAN | |
so you can access the C<gettext> C functions you've heard are standard | |
for localization tasks. | |
And you write: | |
printf(gettext("I scanned %g %s."), | |
$dir_scan_count, | |
$dir_scan_count == 1 ? | |
gettext("directory") : gettext("directories"), | |
); | |
But you then read in the gettext manual (Drepper, Miller, and Pinard 1995) | |
that this is not a good idea, since how a single word like "directory" | |
or "directories" is translated may depend on context -- and this is | |
true, since in a case language like German or Russian, you'd may need | |
these words with a different case ending in the first instance (where the | |
word is the object of a verb) than in the second instance, which you haven't even | |
gotten to yet (where the word is the object of a preposition, "in %g | |
directories") -- assuming these keep the same syntax when translated | |
into those languages. | |
So, on the advice of the gettext manual, you rewrite: | |
printf( $dir_scan_count == 1 ? | |
gettext("I scanned %g directory.") : | |
gettext("I scanned %g directories."), | |
$dir_scan_count ); | |
So, you email your various translators (the boss decides that the | |
languages du jour are Chinese, Arabic, Russian, and Italian, so you | |
have one translator for each), asking for translations for "I scanned | |
%g directory." and "I scanned %g directories.". When they reply, | |
you'll put that in the lexicons for gettext to use when it localizes | |
your software, so that when the user is running under the "zh" | |
(Chinese) locale, gettext("I scanned %g directory.") will return the | |
appropriate Chinese text, with a "%g" in there where printf can then | |
interpolate $dir_scan. | |
Your Chinese translator emails right back -- he says both of these | |
phrases translate to the same thing in Chinese, because, in linguistic | |
jargon, Chinese "doesn't have number as a grammatical category" -- | |
whereas English does. That is, English has grammatical rules that | |
refer to "number", i.e., whether something is grammatically singular | |
or plural; and one of these rules is the one that forces nouns to take | |
a plural suffix (generally "s") when in a plural context, as they are when | |
they follow a number other than "one" (including, oddly enough, "zero"). | |
Chinese has no such rules, and so has just the one phrase where English | |
has two. But, no problem, you can have this one Chinese phrase appear | |
as the translation for the two English phrases in the "zh" gettext | |
lexicon for your program. | |
Emboldened by this, you dive into the second phrase that your software | |
needs to output: "Your query matched 10 files in 4 directories.". You notice | |
that if you want to treat phrases as indivisible, as the gettext | |
manual wisely advises, you need four cases now, instead of two, to | |
cover the permutations of singular and plural on the two items, | |
$dir_count and $file_count. So you try this: | |
printf( $file_count == 1 ? | |
( $directory_count == 1 ? | |
gettext("Your query matched %g file in %g directory.") : | |
gettext("Your query matched %g file in %g directories.") ) : | |
( $directory_count == 1 ? | |
gettext("Your query matched %g files in %g directory.") : | |
gettext("Your query matched %g files in %g directories.") ), | |
$file_count, $directory_count, | |
); | |
(The case of "1 file in 2 [or more] directories" could, I suppose, | |
occur in the case of symlinking or something of the sort.) | |
It occurs to you that this is not the prettiest code you've ever | |
written, but this seems the way to go. You mail off to the | |
translators asking for translations for these four cases. The | |
Chinese guy replies with the one phrase that these all translate to in | |
Chinese, and that phrase has two "%g"s in it, as it should -- but | |
there's a problem. He translates it word-for-word back: "In %g | |
directories contains %g files match your query." The %g | |
slots are in an order reverse to what they are in English. You wonder | |
how you'll get gettext to handle that. | |
But you put it aside for the moment, and optimistically hope that the | |
other translators won't have this problem, and that their languages | |
will be better behaved -- i.e., that they will be just like English. | |
But the Arabic translator is the next to write back. First off, your | |
code for "I scanned %g directory." or "I scanned %g directories." | |
assumes there's only singular or plural. But, to use linguistic | |
jargon again, Arabic has grammatical number, like English (but unlike | |
Chinese), but it's a three-term category: singular, dual, and plural. | |
In other words, the way you say "directory" depends on whether there's | |
one directory, or I<two> of them, or I<more than two> of them. Your | |
test of C<($directory == 1)> no longer does the job. And it means | |
that where English's grammatical category of number necessitates | |
only the two permutations of the first sentence based on "directory | |
[singular]" and "directories [plural]", Arabic has three -- and, | |
worse, in the second sentence ("Your query matched %g file in %g | |
directory."), where English has four, Arabic has nine. You sense | |
an unwelcome, exponential trend taking shape. | |
Your Italian translator emails you back and says that "I searched 0 | |
directories" (a possible English output of your program) is stilted, | |
and if you think that's fine English, that's your problem, but that | |
I<just will not do> in the language of Dante. He insists that where | |
$directory_count is 0, your program should produce the Italian text | |
for "I I<didn't> scan I<any> directories.". And ditto for "I didn't | |
match any files in any directories", although he says the last part | |
about "in any directories" should probably just be left off. | |
You wonder how you'll get gettext to handle this; to accommodate the | |
ways Arabic, Chinese, and Italian deal with numbers in just these few | |
very simple phrases, you need to write code that will ask gettext for | |
different queries depending on whether the numerical values in | |
question are 1, 2, more than 2, or in some cases 0, and you still haven't | |
figured out the problem with the different word order in Chinese. | |
Then your Russian translator calls on the phone, to I<personally> tell | |
you the bad news about how really unpleasant your life is about to | |
become: | |
Russian, like German or Latin, is an inflectional language; that is, nouns | |
and adjectives have to take endings that depend on their case | |
(i.e., nominative, accusative, genitive, etc...) -- which is roughly a matter of | |
what role they have in syntax of the sentence -- | |
as well as on the grammatical gender (i.e., masculine, feminine, neuter) | |
and number (i.e., singular or plural) of the noun, as well as on the | |
declension class of the noun. But unlike with most other inflected languages, | |
putting a number-phrase (like "ten" or "forty-three", or their Arabic | |
numeral equivalents) in front of noun in Russian can change the case and | |
number that noun is, and therefore the endings you have to put on it. | |
He elaborates: In "I scanned %g directories", you'd I<expect> | |
"directories" to be in the accusative case (since it is the direct | |
object in the sentence) and the plural number, | |
except where $directory_count is 1, then you'd expect the singular, of | |
course. Just like Latin or German. I<But!> Where $directory_count % | |
10 is 1 ("%" for modulo, remember), assuming $directory count is an | |
integer, and except where $directory_count % 100 is 11, "directories" | |
is forced to become grammatically singular, which means it gets the | |
ending for the accusative singular... You begin to visualize the code | |
it'd take to test for the problem so far, I<and still work for Chinese | |
and Arabic and Italian>, and how many gettext items that'd take, but | |
he keeps going... But where $directory_count % 10 is 2, 3, or 4 | |
(except where $directory_count % 100 is 12, 13, or 14), the word for | |
"directories" is forced to be genitive singular -- which means another | |
ending... The room begins to spin around you, slowly at first... But | |
with I<all other> integer values, since "directory" is an inanimate | |
noun, when preceded by a number and in the nominative or accusative | |
cases (as it is here, just your luck!), it does stay plural, but it is | |
forced into the genitive case -- yet another ending... And | |
you never hear him get to the part about how you're going to run into | |
similar (but maybe subtly different) problems with other Slavic | |
languages like Polish, because the floor comes up to meet you, and you | |
fade into unconsciousness. | |
The above cautionary tale relates how an attempt at localization can | |
lead from programmer consternation, to program obfuscation, to a need | |
for sedation. But careful evaluation shows that your choice of tools | |
merely needed further consideration. | |
=head2 The Linguistic View | |
=over | |
"It is more complicated than you think." | |
-- The Eighth Networking Truth, from RFC 1925 | |
=back | |
The field of Linguistics has expended a great deal of effort over the | |
past century trying to find grammatical patterns which hold across | |
languages; it's been a constant process | |
of people making generalizations that should apply to all languages, | |
only to find out that, all too often, these generalizations fail -- | |
sometimes failing for just a few languages, sometimes whole classes of | |
languages, and sometimes nearly every language in the world except | |
English. Broad statistical trends are evident in what the "average | |
language" is like as far as what its rules can look like, must look | |
like, and cannot look like. But the "average language" is just as | |
unreal a concept as the "average person" -- it runs up against the | |
fact no language (or person) is, in fact, average. The wisdom of past | |
experience leads us to believe that any given language can do whatever | |
it wants, in any order, with appeal to any kind of grammatical | |
categories wants -- case, number, tense, real or metaphoric | |
characteristics of the things that words refer to, arbitrary or | |
predictable classifications of words based on what endings or prefixes | |
they can take, degree or means of certainty about the truth of | |
statements expressed, and so on, ad infinitum. | |
Mercifully, most localization tasks are a matter of finding ways to | |
translate whole phrases, generally sentences, where the context is | |
relatively set, and where the only variation in content is I<usually> | |
in a number being expressed -- as in the example sentences above. | |
Translating specific, fully-formed sentences is, in practice, fairly | |
foolproof -- which is good, because that's what's in the phrasebooks | |
that so many tourists rely on. Now, a given phrase (whether in a | |
phrasebook or in a gettext lexicon) in one language I<might> have a | |
greater or lesser applicability than that phrase's translation into | |
another language -- for example, strictly speaking, in Arabic, the | |
"your" in "Your query matched..." would take a different form | |
depending on whether the user is male or female; so the Arabic | |
translation "your[feminine] query" is applicable in fewer cases than | |
the corresponding English phrase, which doesn't distinguish the user's | |
gender. (In practice, it's not feasible to have a program know the | |
user's gender, so the masculine "you" in Arabic is usually used, by | |
default.) | |
But in general, such surprises are rare when entire sentences are | |
being translated, especially when the functional context is restricted | |
to that of a computer interacting with a user either to convey a fact | |
or to prompt for a piece of information. So, for purposes of | |
localization, translation by phrase (generally by sentence) is both the | |
simplest and the least problematic. | |
=head2 Breaking gettext | |
=over | |
"It Has To Work." | |
-- First Networking Truth, RFC 1925 | |
=back | |
Consider that sentences in a tourist phrasebook are of two types: ones | |
like "How do I get to the marketplace?" that don't have any blanks to | |
fill in, and ones like "How much do these ___ cost?", where there's | |
one or more blanks to fill in (and these are usually linked to a | |
list of words that you can put in that blank: "fish", "potatoes", | |
"tomatoes", etc.). The ones with no blanks are no problem, but the | |
fill-in-the-blank ones may not be really straightforward. If it's a | |
Swahili phrasebook, for example, the authors probably didn't bother to | |
tell you the complicated ways that the verb "cost" changes its | |
inflectional prefix depending on the noun you're putting in the blank. | |
The trader in the marketplace will still understand what you're saying if | |
you say "how much do these potatoes cost?" with the wrong | |
inflectional prefix on "cost". After all, I<you> can't speak proper Swahili, | |
I<you're> just a tourist. But while tourists can be stupid, computers | |
are supposed to be smart; the computer should be able to fill in the | |
blank, and still have the results be grammatical. | |
In other words, a phrasebook entry takes some values as parameters | |
(the things that you fill in the blank or blanks), and provides a value | |
based on these parameters, where the way you get that final value from | |
the given values can, properly speaking, involve an arbitrarily | |
complex series of operations. (In the case of Chinese, it'd be not at | |
all complex, at least in cases like the examples at the beginning of | |
this article; whereas in the case of Russian it'd be a rather complex | |
series of operations. And in some languages, the | |
complexity could be spread around differently: while the act of | |
putting a number-expression in front of a noun phrase might not be | |
complex by itself, it may change how you have to, for example, inflect | |
a verb elsewhere in the sentence. This is what in syntax is called | |
"long-distance dependencies".) | |
This talk of parameters and arbitrary complexity is just another way | |
to say that an entry in a phrasebook is what in a programming language | |
would be called a "function". Just so you don't miss it, this is the | |
crux of this article: I<A phrase is a function; a phrasebook is a | |
bunch of functions.> | |
The reason that using gettext runs into walls (as in the above | |
second-person horror story) is that you're trying to use a string (or | |
worse, a choice among a bunch of strings) to do what you really need a | |
function for -- which is futile. Preforming (s)printf interpolation | |
on the strings which you get back from gettext does allow you to do I<some> | |
common things passably well... sometimes... sort of; but, to paraphrase | |
what some people say about C<csh> script programming, "it fools you | |
into thinking you can use it for real things, but you can't, and you | |
don't discover this until you've already spent too much time trying, | |
and by then it's too late." | |
=head2 Replacing gettext | |
So, what needs to replace gettext is a system that supports lexicons | |
of functions instead of lexicons of strings. An entry in a lexicon | |
from such a system should I<not> look like this: | |
"J'ai trouv\xE9 %g fichiers dans %g r\xE9pertoires" | |
[\xE9 is e-acute in Latin-1. Some pod renderers would | |
scream if I used the actual character here. -- SB] | |
but instead like this, bearing in mind that this is just a first stab: | |
sub I_found_X1_files_in_X2_directories { | |
my( $files, $dirs ) = @_[0,1]; | |
$files = sprintf("%g %s", $files, | |
$files == 1 ? 'fichier' : 'fichiers'); | |
$dirs = sprintf("%g %s", $dirs, | |
$dirs == 1 ? "r\xE9pertoire" : "r\xE9pertoires"); | |
return "J'ai trouv\xE9 $files dans $dirs."; | |
} | |
Now, there's no particularly obvious way to store anything but strings | |
in a gettext lexicon; so it looks like we just have to start over and | |
make something better, from scratch. I call my shot at a | |
gettext-replacement system "Maketext", or, in CPAN terms, | |
Locale::Maketext. | |
When designing Maketext, I chose to plan its main features in terms of | |
"buzzword compliance". And here are the buzzwords: | |
=head2 Buzzwords: Abstraction and Encapsulation | |
The complexity of the language you're trying to output a phrase in is | |
entirely abstracted inside (and encapsulated within) the Maketext module | |
for that interface. When you call: | |
print $lang->maketext("You have [quant,_1,piece] of new mail.", | |
scalar(@messages)); | |
you don't know (and in fact can't easily find out) whether this will | |
involve lots of figuring, as in Russian (if $lang is a handle to the | |
Russian module), or relatively little, as in Chinese. That kind of | |
abstraction and encapsulation may encourage other pleasant buzzwords | |
like modularization and stratification, depending on what design | |
decisions you make. | |
=head2 Buzzword: Isomorphism | |
"Isomorphism" means "having the same structure or form"; in discussions | |
of program design, the word takes on the special, specific meaning that | |
your implementation of a solution to a problem I<has the same | |
structure> as, say, an informal verbal description of the solution, or | |
maybe of the problem itself. Isomorphism is, all things considered, | |
a good thing -- it's what problem-solving (and solution-implementing) | |
should look like. | |
What's wrong the with gettext-using code like this... | |
printf( $file_count == 1 ? | |
( $directory_count == 1 ? | |
"Your query matched %g file in %g directory." : | |
"Your query matched %g file in %g directories." ) : | |
( $directory_count == 1 ? | |
"Your query matched %g files in %g directory." : | |
"Your query matched %g files in %g directories." ), | |
$file_count, $directory_count, | |
); | |
is first off that it's not well abstracted -- these ways of testing | |
for grammatical number (as in the expressions like C<foo == 1 ? | |
singular_form : plural_form>) should be abstracted to each language | |
module, since how you get grammatical number is language-specific. | |
But second off, it's not isomorphic -- the "solution" (i.e., the | |
phrasebook entries) for Chinese maps from these four English phrases to | |
the one Chinese phrase that fits for all of them. In other words, the | |
informal solution would be "The way to say what you want in Chinese is | |
with the one phrase 'For your question, in Y directories you would | |
find X files'" -- and so the implemented solution should be, | |
isomorphically, just a straightforward way to spit out that one | |
phrase, with numerals properly interpolated. It shouldn't have to map | |
from the complexity of other languages to the simplicity of this one. | |
=head2 Buzzword: Inheritance | |
There's a great deal of reuse possible for sharing of phrases between | |
modules for related dialects, or for sharing of auxiliary functions | |
between related languages. (By "auxiliary functions", I mean | |
functions that don't produce phrase-text, but which, say, return an | |
answer to "does this number require a plural noun after it?". Such | |
auxiliary functions would be used in the internal logic of functions | |
that actually do produce phrase-text.) | |
In the case of sharing phrases, consider that you have an interface | |
already localized for American English (probably by having been | |
written with that as the native locale, but that's incidental). | |
Localizing it for UK English should, in practical terms, be just a | |
matter of running it past a British person with the instructions to | |
indicate what few phrases would benefit from a change in spelling or | |
possibly minor rewording. In that case, you should be able to put in | |
the UK English localization module I<only> those phrases that are | |
UK-specific, and for all the rest, I<inherit> from the American | |
English module. (And I expect this same situation would apply with | |
Brazilian and Continental Portugese, possibly with some I<very> | |
closely related languages like Czech and Slovak, and possibly with the | |
slightly different "versions" of written Mandarin Chinese, as I hear exist in | |
Taiwan and mainland China.) | |
As to sharing of auxiliary functions, consider the problem of Russian | |
numbers from the beginning of this article; obviously, you'd want to | |
write only once the hairy code that, given a numeric value, would | |
return some specification of which case and number a given quantified | |
noun should use. But suppose that you discover, while localizing an | |
interface for, say, Ukrainian (a Slavic language related to Russian, | |
spoken by several million people, many of whom would be relieved to | |
find that your Web site's or software's interface is available in | |
their language), that the rules in Ukrainian are the same as in Russian | |
for quantification, and probably for many other grammatical functions. | |
While there may well be no phrases in common between Russian and | |
Ukrainian, you could still choose to have the Ukrainian module inherit | |
from the Russian module, just for the sake of inheriting all the | |
various grammatical methods. Or, probably better organizationally, | |
you could move those functions to a module called C<_E_Slavic> or | |
something, which Russian and Ukrainian could inherit useful functions | |
from, but which would (presumably) provide no lexicon. | |
=head2 Buzzword: Concision | |
Okay, concision isn't a buzzword. But it should be, so I decree that | |
as a new buzzword, "concision" means that simple common things should | |
be expressible in very few lines (or maybe even just a few characters) | |
of code -- call it a special case of "making simple things easy and | |
hard things possible", and see also the role it played in the | |
MIDI::Simple language, discussed elsewhere in this issue [TPJ#13]. | |
Consider our first stab at an entry in our "phrasebook of functions": | |
sub I_found_X1_files_in_X2_directories { | |
my( $files, $dirs ) = @_[0,1]; | |
$files = sprintf("%g %s", $files, | |
$files == 1 ? 'fichier' : 'fichiers'); | |
$dirs = sprintf("%g %s", $dirs, | |
$dirs == 1 ? "r\xE9pertoire" : "r\xE9pertoires"); | |
return "J'ai trouv\xE9 $files dans $dirs."; | |
} | |
You may sense that a lexicon (to use a non-committal catch-all term for a | |
collection of things you know how to say, regardless of whether they're | |
phrases or words) consisting of functions I<expressed> as above would | |
make for rather long-winded and repetitive code -- even if you wisely | |
rewrote this to have quantification (as we call adding a number | |
expression to a noun phrase) be a function called like: | |
sub I_found_X1_files_in_X2_directories { | |
my( $files, $dirs ) = @_[0,1]; | |
$files = quant($files, "fichier"); | |
$dirs = quant($dirs, "r\xE9pertoire"); | |
return "J'ai trouv\xE9 $files dans $dirs."; | |
} | |
And you may also sense that you do not want to bother your translators | |
with having to write Perl code -- you'd much rather that they spend | |
their I<very costly time> on just translation. And this is to say | |
nothing of the near impossibility of finding a commercial translator | |
who would know even simple Perl. | |
In a first-hack implementation of Maketext, each language-module's | |
lexicon looked like this: | |
%Lexicon = ( | |
"I found %g files in %g directories" | |
=> sub { | |
my( $files, $dirs ) = @_[0,1]; | |
$files = quant($files, "fichier"); | |
$dirs = quant($dirs, "r\xE9pertoire"); | |
return "J'ai trouv\xE9 $files dans $dirs."; | |
}, | |
... and so on with other phrase => sub mappings ... | |
); | |
but I immediately went looking for some more concise way to basically | |
denote the same phrase-function -- a way that would also serve to | |
concisely denote I<most> phrase-functions in the lexicon for I<most> | |
languages. After much time and even some actual thought, I decided on | |
this system: | |
* Where a value in a %Lexicon hash is a contentful string instead of | |
an anonymous sub (or, conceivably, a coderef), it would be interpreted | |
as a sort of shorthand expression of what the sub does. When accessed | |
for the first time in a session, it is parsed, turned into Perl code, | |
and then eval'd into an anonymous sub; then that sub replaces the | |
original string in that lexicon. (That way, the work of parsing and | |
evaling the shorthand form for a given phrase is done no more than | |
once per session.) | |
* Calls to C<maketext> (as Maketext's main function is called) happen | |
thru a "language session handle", notionally very much like an IO | |
handle, in that you open one at the start of the session, and use it | |
for "sending signals" to an object in order to have it return the text | |
you want. | |
So, this: | |
$lang->maketext("You have [quant,_1,piece] of new mail.", | |
scalar(@messages)); | |
basically means this: look in the lexicon for $lang (which may inherit | |
from any number of other lexicons), and find the function that we | |
happen to associate with the string "You have [quant,_1,piece] of new | |
mail" (which is, and should be, a functioning "shorthand" for this | |
function in the native locale -- English in this case). If you find | |
such a function, call it with $lang as its first parameter (as if it | |
were a method), and then a copy of scalar(@messages) as its second, | |
and then return that value. If that function was found, but was in | |
string shorthand instead of being a fully specified function, parse it | |
and make it into a function before calling it the first time. | |
* The shorthand uses code in brackets to indicate method calls that | |
should be performed. A full explanation is not in order here, but a | |
few examples will suffice: | |
"You have [quant,_1,piece] of new mail." | |
The above code is shorthand for, and will be interpreted as, | |
this: | |
sub { | |
my $handle = $_[0]; | |
my(@params) = @_; | |
return join '', | |
"You have ", | |
$handle->quant($params[1], 'piece'), | |
"of new mail."; | |
} | |
where "quant" is the name of a method you're using to quantify the | |
noun "piece" with the number $params[0]. | |
A string with no brackety calls, like this: | |
"Your search expression was malformed." | |
is somewhat of a degenerate case, and just gets turned into: | |
sub { return "Your search expression was malformed." } | |
However, not everything you can write in Perl code can be written in | |
the above shorthand system -- not by a long shot. For example, consider | |
the Italian translator from the beginning of this article, who wanted | |
the Italian for "I didn't find any files" as a special case, instead | |
of "I found 0 files". That couldn't be specified (at least not easily | |
or simply) in our shorthand system, and it would have to be written | |
out in full, like this: | |
sub { # pretend the English strings are in Italian | |
my($handle, $files, $dirs) = @_[0,1,2]; | |
return "I didn't find any files" unless $files; | |
return join '', | |
"I found ", | |
$handle->quant($files, 'file'), | |
" in ", | |
$handle->quant($dirs, 'directory'), | |
"."; | |
} | |
Next to a lexicon full of shorthand code, that sort of sticks out like a | |
sore thumb -- but this I<is> a special case, after all; and at least | |
it's possible, if not as concise as usual. | |
As to how you'd implement the Russian example from the beginning of | |
the article, well, There's More Than One Way To Do It, but it could be | |
something like this (using English words for Russian, just so you know | |
what's going on): | |
"I [quant,_1,directory,accusative] scanned." | |
This shifts the burden of complexity off to the quant method. That | |
method's parameters are: the numeric value it's going to use to | |
quantify something; the Russian word it's going to quantify; and the | |
parameter "accusative", which you're using to mean that this | |
sentence's syntax wants a noun in the accusative case there, although | |
that quantification method may have to overrule, for grammatical | |
reasons you may recall from the beginning of this article. | |
Now, the Russian quant method here is responsible not only for | |
implementing the strange logic necessary for figuring out how Russian | |
number-phrases impose case and number on their noun-phrases, but also | |
for inflecting the Russian word for "directory". How that inflection | |
is to be carried out is no small issue, and among the solutions I've | |
seen, some (like variations on a simple lookup in a hash where all | |
possible forms are provided for all necessary words) are | |
straightforward but I<can> become cumbersome when you need to inflect | |
more than a few dozen words; and other solutions (like using | |
algorithms to model the inflections, storing only root forms and | |
irregularities) I<can> involve more overhead than is justifiable for | |
all but the largest lexicons. | |
Mercifully, this design decision becomes crucial only in the hairiest | |
of inflected languages, of which Russian is by no means the I<worst> case | |
scenario, but is worse than most. Most languages have simpler | |
inflection systems; for example, in English or Swahili, there are | |
generally no more than two possible inflected forms for a given noun | |
("error/errors"; "kosa/makosa"), and the | |
rules for producing these forms are fairly simple -- or at least, | |
simple rules can be formulated that work for most words, and you can | |
then treat the exceptions as just "irregular", at least relative to | |
your ad hoc rules. A simpler inflection system (simpler rules, fewer | |
forms) means that design decisions are less crucial to maintaining | |
sanity, whereas the same decisions could incur | |
overhead-versus-scalability problems in languages like Russian. It | |
may I<also> be likely that code (possibly in Perl, as with | |
Lingua::EN::Inflect, for English nouns) has already | |
been written for the language in question, whether simple or complex. | |
Moreover, a third possibility may even be simpler than anything | |
discussed above: "Just require that all possible (or at least | |
applicable) forms be provided in the call to the given language's quant | |
method, as in:" | |
"I found [quant,_1,file,files]." | |
That way, quant just has to chose which form it needs, without having | |
to look up or generate anything. While possibly not optimal for | |
Russian, this should work well for most other languages, where | |
quantification is not as complicated an operation. | |
=head2 The Devil in the Details | |
There's plenty more to Maketext than described above -- for example, | |
there's the details of how language tags ("en-US", "i-pwn", "fi", | |
etc.) or locale IDs ("en_US") interact with actual module naming | |
("BogoQuery/Locale/en_us.pm"), and what magic can ensue; there's the | |
details of how to record (and possibly negotiate) what character | |
encoding Maketext will return text in (UTF8? Latin-1? KOI8?). There's | |
the interesting fact that Maketext is for localization, but nowhere | |
actually has a "C<use locale;>" anywhere in it. For the curious, | |
there's the somewhat frightening details of how I actually | |
implement something like data inheritance so that searches across | |
modules' %Lexicon hashes can parallel how Perl implements method | |
inheritance. | |
And, most importantly, there's all the practical details of how to | |
actually go about deriving from Maketext so you can use it for your | |
interfaces, and the various tools and conventions for starting out and | |
maintaining individual language modules. | |
That is all covered in the documentation for Locale::Maketext and the | |
modules that come with it, available in CPAN. After having read this | |
article, which covers the why's of Maketext, the documentation, | |
which covers the how's of it, should be quite straightforward. | |
=head2 The Proof in the Pudding: Localizing Web Sites | |
Maketext and gettext have a notable difference: gettext is in C, | |
accessible thru C library calls, whereas Maketext is in Perl, and | |
really can't work without a Perl interpreter (although I suppose | |
something like it could be written for C). Accidents of history (and | |
not necessarily lucky ones) have made C++ the most common language for | |
the implementation of applications like word processors, Web browsers, | |
and even many in-house applications like custom query systems. Current | |
conditions make it somewhat unlikely that the next one of any of these | |
kinds of applications will be written in Perl, albeit clearly more for | |
reasons of custom and inertia than out of consideration of what is the | |
right tool for the job. | |
However, other accidents of history have made Perl a well-accepted | |
language for design of server-side programs (generally in CGI form) | |
for Web site interfaces. Localization of static pages in Web sites is | |
trivial, feasible either with simple language-negotiation features in | |
servers like Apache, or with some kind of server-side inclusions of | |
language-appropriate text into layout templates. However, I think | |
that the localization of Perl-based search systems (or other kinds of | |
dynamic content) in Web sites, be they public or access-restricted, | |
is where Maketext will see the greatest use. | |
I presume that it would be only the exceptional Web site that gets | |
localized for English I<and> Chinese I<and> Italian I<and> Arabic | |
I<and> Russian, to recall the languages from the beginning of this | |
article -- to say nothing of German, Spanish, French, Japanese, | |
Finnish, and Hindi, to name a few languages that benefit from large | |
numbers of programmers or Web viewers or both. | |
However, the ever-increasing internationalization of the Web (whether | |
measured in terms of amount of content, of numbers of content writers | |
or programmers, or of size of content audiences) makes it increasingly | |
likely that the interface to the average Web-based dynamic content | |
service will be localized for two or maybe three languages. It is my | |
hope that Maketext will make that task as simple as possible, and will | |
remove previous barriers to localization for languages dissimilar to | |
English. | |
__END__ | |
Sean M. Burke (sburkeE<64>cpan.org) has a Master's in linguistics | |
from Northwestern University; he specializes in language technology. | |
Jordan Lachler (lachlerE<64>unm.edu) is a PhD student in the Department of | |
Linguistics at the University of New Mexico; he specializes in | |
morphology and pedagogy of North American native languages. | |
=head2 References | |
Alvestrand, Harald Tveit. 1995. I<RFC 1766: Tags for the | |
Identification of Languages.> | |
C<L<http://www.ietf.org/rfc/rfc1766.txt>> | |
[Now see RFC 3066.] | |
Callon, Ross, editor. 1996. I<RFC 1925: The Twelve | |
Networking Truths.> | |
C<L<http://www.ietf.org/rfc/rfc1925.txt>> | |
Drepper, Ulrich, Peter Miller, | |
and FranE<ccedil>ois Pinard. 1995-2001. GNU | |
C<gettext>. Available in C<L<ftp://prep.ai.mit.edu/pub/gnu/>>, with | |
extensive docs in the distribution tarball. [Since | |
I wrote this article in 1998, I now see that the | |
gettext docs are now trying more to come to terms with | |
plurality. Whether useful conclusions have come from it | |
is another question altogether. -- SMB, May 2001] | |
Forbes, Nevill. 1964. I<Russian Grammar.> Third Edition, revised | |
by J. C. Dumbreck. Oxford University Press. | |
=cut | |
#End | |