776 lines
35 KiB
Plaintext
776 lines
35 KiB
Plaintext
# 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
|
|
|