summaryrefslogtreecommitdiff
path: root/Master/tlpkg/tlperl/lib/Locale/Maketext.pod
diff options
context:
space:
mode:
Diffstat (limited to 'Master/tlpkg/tlperl/lib/Locale/Maketext.pod')
-rw-r--r--Master/tlpkg/tlperl/lib/Locale/Maketext.pod1354
1 files changed, 0 insertions, 1354 deletions
diff --git a/Master/tlpkg/tlperl/lib/Locale/Maketext.pod b/Master/tlpkg/tlperl/lib/Locale/Maketext.pod
deleted file mode 100644
index 3ef9c3a5a9b..00000000000
--- a/Master/tlpkg/tlperl/lib/Locale/Maketext.pod
+++ /dev/null
@@ -1,1354 +0,0 @@
-
-# Time-stamp: "2004-01-11 18:35:34 AST"
-
-=head1 NAME
-
-Locale::Maketext - framework for localization
-
-=head1 SYNOPSIS
-
- package MyProgram;
- use strict;
- use MyProgram::L10N;
- # ...which inherits from Locale::Maketext
- my $lh = MyProgram::L10N->get_handle() || die "What language?";
- ...
- # And then any messages your program emits, like:
- warn $lh->maketext( "Can't open file [_1]: [_2]\n", $f, $! );
- ...
-
-=head1 DESCRIPTION
-
-It is a common feature of applications (whether run directly,
-or via the Web) for them to be "localized" -- i.e., for them
-to a present an English interface to an English-speaker, a German
-interface to a German-speaker, and so on for all languages it's
-programmed with. Locale::Maketext
-is a framework for software localization; it provides you with the
-tools for organizing and accessing the bits of text and text-processing
-code that you need for producing localized applications.
-
-In order to make sense of Maketext and how all its
-components fit together, you should probably
-go read L<Locale::Maketext::TPJ13|Locale::Maketext::TPJ13>, and
-I<then> read the following documentation.
-
-You may also want to read over the source for C<File::Findgrep>
-and its constituent modules -- they are a complete (if small)
-example application that uses Maketext.
-
-=head1 QUICK OVERVIEW
-
-The basic design of Locale::Maketext is object-oriented, and
-Locale::Maketext is an abstract base class, from which you
-derive a "project class".
-The project class (with a name like "TkBocciBall::Localize",
-which you then use in your module) is in turn the base class
-for all the "language classes" for your project
-(with names "TkBocciBall::Localize::it",
-"TkBocciBall::Localize::en",
-"TkBocciBall::Localize::fr", etc.).
-
-A language class is
-a class containing a lexicon of phrases as class data,
-and possibly also some methods that are of use in interpreting
-phrases in the lexicon, or otherwise dealing with text in that
-language.
-
-An object belonging to a language class is called a "language
-handle"; it's typically a flyweight object.
-
-The normal course of action is to call:
-
- use TkBocciBall::Localize; # the localization project class
- $lh = TkBocciBall::Localize->get_handle();
- # Depending on the user's locale, etc., this will
- # make a language handle from among the classes available,
- # and any defaults that you declare.
- die "Couldn't make a language handle??" unless $lh;
-
-From then on, you use the C<maketext> function to access
-entries in whatever lexicon(s) belong to the language handle
-you got. So, this:
-
- print $lh->maketext("You won!"), "\n";
-
-...emits the right text for this language. If the object
-in C<$lh> belongs to class "TkBocciBall::Localize::fr" and
-%TkBocciBall::Localize::fr::Lexicon contains C<("You won!"
-=E<gt> "Tu as gagnE<eacute>!")>, then the above
-code happily tells the user "Tu as gagnE<eacute>!".
-
-=head1 METHODS
-
-Locale::Maketext offers a variety of methods, which fall
-into three categories:
-
-=over
-
-=item *
-
-Methods to do with constructing language handles.
-
-=item *
-
-C<maketext> and other methods to do with accessing %Lexicon data
-for a given language handle.
-
-=item *
-
-Methods that you may find it handy to use, from routines of
-yours that you put in %Lexicon entries.
-
-=back
-
-These are covered in the following section.
-
-=head2 Construction Methods
-
-These are to do with constructing a language handle:
-
-=over
-
-=item *
-
-$lh = YourProjClass->get_handle( ...langtags... ) || die "lg-handle?";
-
-This tries loading classes based on the language-tags you give (like
-C<("en-US", "sk", "kon", "es-MX", "ja", "i-klingon")>, and for the first class
-that succeeds, returns YourProjClass::I<language>->new().
-
-If it runs thru the entire given list of language-tags, and finds no classes
-for those exact terms, it then tries "superordinate" language classes.
-So if no "en-US" class (i.e., YourProjClass::en_us)
-was found, nor classes for anything else in that list, we then try
-its superordinate, "en" (i.e., YourProjClass::en), and so on thru
-the other language-tags in the given list: "es".
-(The other language-tags in our example list:
-happen to have no superordinates.)
-
-If none of those language-tags leads to loadable classes, we then
-try classes derived from YourProjClass->fallback_languages() and
-then if nothing comes of that, we use classes named by
-YourProjClass->fallback_language_classes(). Then in the (probably
-quite unlikely) event that that fails, we just return undef.
-
-=item *
-
-$lh = YourProjClass->get_handleB<()> || die "lg-handle?";
-
-When C<get_handle> is called with an empty parameter list, magic happens:
-
-If C<get_handle> senses that it's running in program that was
-invoked as a CGI, then it tries to get language-tags out of the
-environment variable "HTTP_ACCEPT_LANGUAGE", and it pretends that
-those were the languages passed as parameters to C<get_handle>.
-
-Otherwise (i.e., if not a CGI), this tries various OS-specific ways
-to get the language-tags for the current locale/language, and then
-pretends that those were the value(s) passed to C<get_handle>.
-
-Currently this OS-specific stuff consists of looking in the environment
-variables "LANG" and "LANGUAGE"; and on MSWin machines (where those
-variables are typically unused), this also tries using
-the module Win32::Locale to get a language-tag for whatever language/locale
-is currently selected in the "Regional Settings" (or "International"?)
-Control Panel. I welcome further
-suggestions for making this do the Right Thing under other operating
-systems that support localization.
-
-If you're using localization in an application that keeps a configuration
-file, you might consider something like this in your project class:
-
- sub get_handle_via_config {
- my $class = $_[0];
- my $chosen_language = $Config_settings{'language'};
- my $lh;
- if($chosen_language) {
- $lh = $class->get_handle($chosen_language)
- || die "No language handle for \"$chosen_language\""
- . " or the like";
- } else {
- # Config file missing, maybe?
- $lh = $class->get_handle()
- || die "Can't get a language handle";
- }
- return $lh;
- }
-
-=item *
-
-$lh = YourProjClass::langname->new();
-
-This constructs a language handle. You usually B<don't> call this
-directly, but instead let C<get_handle> find a language class to C<use>
-and to then call ->new on.
-
-=item *
-
-$lh->init();
-
-This is called by ->new to initialize newly-constructed language handles.
-If you define an init method in your class, remember that it's usually
-considered a good idea to call $lh->SUPER::init in it (presumably at the
-beginning), so that all classes get a chance to initialize a new object
-however they see fit.
-
-=item *
-
-YourProjClass->fallback_languages()
-
-C<get_handle> appends the return value of this to the end of
-whatever list of languages you pass C<get_handle>. Unless
-you override this method, your project class
-will inherit Locale::Maketext's C<fallback_languages>, which
-currently returns C<('i-default', 'en', 'en-US')>.
-("i-default" is defined in RFC 2277).
-
-This method (by having it return the name
-of a language-tag that has an existing language class)
-can be used for making sure that
-C<get_handle> will always manage to construct a language
-handle (assuming your language classes are in an appropriate
-@INC directory). Or you can use the next method:
-
-=item *
-
-YourProjClass->fallback_language_classes()
-
-C<get_handle> appends the return value of this to the end
-of the list of classes it will try using. Unless
-you override this method, your project class
-will inherit Locale::Maketext's C<fallback_language_classes>,
-which currently returns an empty list, C<()>.
-By setting this to some value (namely, the name of a loadable
-language class), you can be sure that
-C<get_handle> will always manage to construct a language
-handle.
-
-=back
-
-=head2 The "maketext" Method
-
-This is the most important method in Locale::Maketext:
-
- $text = $lh->maketext(I<key>, ...parameters for this phrase...);
-
-This looks in the %Lexicon of the language handle
-$lh and all its superclasses, looking
-for an entry whose key is the string I<key>. Assuming such
-an entry is found, various things then happen, depending on the
-value found:
-
-If the value is a scalarref, the scalar is dereferenced and returned
-(and any parameters are ignored).
-
-If the value is a coderef, we return &$value($lh, ...parameters...).
-
-If the value is a string that I<doesn't> look like it's in Bracket Notation,
-we return it (after replacing it with a scalarref, in its %Lexicon).
-
-If the value I<does> look like it's in Bracket Notation, then we compile
-it into a sub, replace the string in the %Lexicon with the new coderef,
-and then we return &$new_sub($lh, ...parameters...).
-
-Bracket Notation is discussed in a later section. Note
-that trying to compile a string into Bracket Notation can throw
-an exception if the string is not syntactically valid (say, by not
-balancing brackets right.)
-
-Also, calling &$coderef($lh, ...parameters...) can throw any sort of
-exception (if, say, code in that sub tries to divide by zero). But
-a very common exception occurs when you have Bracket
-Notation text that says to call a method "foo", but there is no such
-method. (E.g., "You have [quaB<tn>,_1,ball]." will throw an exception
-on trying to call $lh->quaB<tn>($_[1],'ball') -- you presumably meant
-"quant".) C<maketext> catches these exceptions, but only to make the
-error message more readable, at which point it rethrows the exception.
-
-An exception I<may> be thrown if I<key> is not found in any
-of $lh's %Lexicon hashes. What happens if a key is not found,
-is discussed in a later section, "Controlling Lookup Failure".
-
-Note that you might find it useful in some cases to override
-the C<maketext> method with an "after method", if you want to
-translate encodings, or even scripts:
-
- package YrProj::zh_cn; # Chinese with PRC-style glyphs
- use base ('YrProj::zh_tw'); # Taiwan-style
- sub maketext {
- my $self = shift(@_);
- my $value = $self->maketext(@_);
- return Chineeze::taiwan2mainland($value);
- }
-
-Or you may want to override it with something that traps
-any exceptions, if that's critical to your program:
-
- sub maketext {
- my($lh, @stuff) = @_;
- my $out;
- eval { $out = $lh->SUPER::maketext(@stuff) };
- return $out unless $@;
- ...otherwise deal with the exception...
- }
-
-Other than those two situations, I don't imagine that
-it's useful to override the C<maketext> method. (If
-you run into a situation where it is useful, I'd be
-interested in hearing about it.)
-
-=over
-
-=item $lh->fail_with I<or> $lh->fail_with(I<PARAM>)
-
-=item $lh->failure_handler_auto
-
-These two methods are discussed in the section "Controlling
-Lookup Failure".
-
-=back
-
-=head2 Utility Methods
-
-These are methods that you may find it handy to use, generally
-from %Lexicon routines of yours (whether expressed as
-Bracket Notation or not).
-
-=over
-
-=item $language->quant($number, $singular)
-
-=item $language->quant($number, $singular, $plural)
-
-=item $language->quant($number, $singular, $plural, $negative)
-
-This is generally meant to be called from inside Bracket Notation
-(which is discussed later), as in
-
- "Your search matched [quant,_1,document]!"
-
-It's for I<quantifying> a noun (i.e., saying how much of it there is,
-while giving the correct form of it). The behavior of this method is
-handy for English and a few other Western European languages, and you
-should override it for languages where it's not suitable. You can feel
-free to read the source, but the current implementation is basically
-as this pseudocode describes:
-
- if $number is 0 and there's a $negative,
- return $negative;
- elsif $number is 1,
- return "1 $singular";
- elsif there's a $plural,
- return "$number $plural";
- else
- return "$number " . $singular . "s";
- #
- # ...except that we actually call numf to
- # stringify $number before returning it.
-
-So for English (with Bracket Notation)
-C<"...[quant,_1,file]..."> is fine (for 0 it returns "0 files",
-for 1 it returns "1 file", and for more it returns "2 files", etc.)
-
-But for "directory", you'd want C<"[quant,_1,directory,directories]">
-so that our elementary C<quant> method doesn't think that the
-plural of "directory" is "directorys". And you might find that the
-output may sound better if you specify a negative form, as in:
-
- "[quant,_1,file,files,No files] matched your query.\n"
-
-Remember to keep in mind verb agreement (or adjectives too, in
-other languages), as in:
-
- "[quant,_1,document] were matched.\n"
-
-Because if _1 is one, you get "1 document B<were> matched".
-An acceptable hack here is to do something like this:
-
- "[quant,_1,document was, documents were] matched.\n"
-
-=item $language->numf($number)
-
-This returns the given number formatted nicely according to
-this language's conventions. Maketext's default method is
-mostly to just take the normal string form of the number
-(applying sprintf "%G" for only very large numbers), and then
-to add commas as necessary. (Except that
-we apply C<tr/,./.,/> if $language->{'numf_comma'} is true;
-that's a bit of a hack that's useful for languages that express
-two million as "2.000.000" and not as "2,000,000").
-
-If you want anything fancier, consider overriding this with something
-that uses L<Number::Format|Number::Format>, or does something else
-entirely.
-
-Note that numf is called by quant for stringifying all quantifying
-numbers.
-
-=item $language->numerate($number, $singular, $plural, $negative)
-
-This returns the given noun form which is appropriate for the quantity
-C<$number> according to this language's conventions. C<numerate> is
-used internally by C<quant> to quantify nouns. Use it directly --
-usually from bracket notation -- to avoid C<quant>'s implicit call to
-C<numf> and output of a numeric quantity.
-
-=item $language->sprintf($format, @items)
-
-This is just a wrapper around Perl's normal C<sprintf> function.
-It's provided so that you can use "sprintf" in Bracket Notation:
-
- "Couldn't access datanode [sprintf,%10x=~[%s~],_1,_2]!\n"
-
-returning...
-
- Couldn't access datanode Stuff=[thangamabob]!
-
-=item $language->language_tag()
-
-Currently this just takes the last bit of C<ref($language)>, turns
-underscores to dashes, and returns it. So if $language is
-an object of class Hee::HOO::Haw::en_us, $language->language_tag()
-returns "en-us". (Yes, the usual representation for that language
-tag is "en-US", but case is I<never> considered meaningful in
-language-tag comparison.)
-
-You may override this as you like; Maketext doesn't use it for
-anything.
-
-=item $language->encoding()
-
-Currently this isn't used for anything, but it's provided
-(with default value of
-C<(ref($language) && $language-E<gt>{'encoding'})) or "iso-8859-1">
-) as a sort of suggestion that it may be useful/necessary to
-associate encodings with your language handles (whether on a
-per-class or even per-handle basis.)
-
-=back
-
-=head2 Language Handle Attributes and Internals
-
-A language handle is a flyweight object -- i.e., it doesn't (necessarily)
-carry any data of interest, other than just being a member of
-whatever class it belongs to.
-
-A language handle is implemented as a blessed hash. Subclasses of yours
-can store whatever data you want in the hash. Currently the only hash
-entry used by any crucial Maketext method is "fail", so feel free to
-use anything else as you like.
-
-B<Remember: Don't be afraid to read the Maketext source if there's
-any point on which this documentation is unclear.> This documentation
-is vastly longer than the module source itself.
-
-=over
-
-=back
-
-=head1 LANGUAGE CLASS HIERARCHIES
-
-These are Locale::Maketext's assumptions about the class
-hierarchy formed by all your language classes:
-
-=over
-
-=item *
-
-You must have a project base class, which you load, and
-which you then use as the first argument in
-the call to YourProjClass->get_handle(...). It should derive
-(whether directly or indirectly) from Locale::Maketext.
-It B<doesn't matter> how you name this class, although assuming this
-is the localization component of your Super Mega Program,
-good names for your project class might be
-SuperMegaProgram::Localization, SuperMegaProgram::L10N,
-SuperMegaProgram::I18N, SuperMegaProgram::International,
-or even SuperMegaProgram::Languages or SuperMegaProgram::Messages.
-
-=item *
-
-Language classes are what YourProjClass->get_handle will try to load.
-It will look for them by taking each language-tag (B<skipping> it
-if it doesn't look like a language-tag or locale-tag!), turning it to
-all lowercase, turning dashes to underscores, and appending it
-to YourProjClass . "::". So this:
-
- $lh = YourProjClass->get_handle(
- 'en-US', 'fr', 'kon', 'i-klingon', 'i-klingon-romanized'
- );
-
-will try loading the classes
-YourProjClass::en_us (note lowercase!), YourProjClass::fr,
-YourProjClass::kon,
-YourProjClass::i_klingon
-and YourProjClass::i_klingon_romanized. (And it'll stop at the
-first one that actually loads.)
-
-=item *
-
-I assume that each language class derives (directly or indirectly)
-from your project class, and also defines its @ISA, its %Lexicon,
-or both. But I anticipate no dire consequences if these assumptions
-do not hold.
-
-=item *
-
-Language classes may derive from other language classes (although they
-should have "use I<Thatclassname>" or "use base qw(I<...classes...>)").
-They may derive from the project
-class. They may derive from some other class altogether. Or via
-multiple inheritance, it may derive from any mixture of these.
-
-=item *
-
-I foresee no problems with having multiple inheritance in
-your hierarchy of language classes. (As usual, however, Perl will
-complain bitterly if you have a cycle in the hierarchy: i.e., if
-any class is its own ancestor.)
-
-=back
-
-=head1 ENTRIES IN EACH LEXICON
-
-A typical %Lexicon entry is meant to signify a phrase,
-taking some number (0 or more) of parameters. An entry
-is meant to be accessed by via
-a string I<key> in $lh->maketext(I<key>, ...parameters...),
-which should return a string that is generally meant for
-be used for "output" to the user -- regardless of whether
-this actually means printing to STDOUT, writing to a file,
-or putting into a GUI widget.
-
-While the key must be a string value (since that's a basic
-restriction that Perl places on hash keys), the value in
-the lexicon can currently be of several types:
-a defined scalar, scalarref, or coderef. The use of these is
-explained above, in the section 'The "maketext" Method', and
-Bracket Notation for strings is discussed in the next section.
-
-While you can use arbitrary unique IDs for lexicon keys
-(like "_min_larger_max_error"), it is often
-useful for if an entry's key is itself a valid value, like
-this example error message:
-
- "Minimum ([_1]) is larger than maximum ([_2])!\n",
-
-Compare this code that uses an arbitrary ID...
-
- die $lh->maketext( "_min_larger_max_error", $min, $max )
- if $min > $max;
-
-...to this code that uses a key-as-value:
-
- die $lh->maketext(
- "Minimum ([_1]) is larger than maximum ([_2])!\n",
- $min, $max
- ) if $min > $max;
-
-The second is, in short, more readable. In particular, it's obvious
-that the number of parameters you're feeding to that phrase (two) is
-the number of parameters that it I<wants> to be fed. (Since you see
-_1 and a _2 being used in the key there.)
-
-Also, once a project is otherwise
-complete and you start to localize it, you can scrape together
-all the various keys you use, and pass it to a translator; and then
-the translator's work will go faster if what he's presented is this:
-
- "Minimum ([_1]) is larger than maximum ([_2])!\n",
- => "", # fill in something here, Jacques!
-
-rather than this more cryptic mess:
-
- "_min_larger_max_error"
- => "", # fill in something here, Jacques
-
-I think that keys as lexicon values makes the completed lexicon
-entries more readable:
-
- "Minimum ([_1]) is larger than maximum ([_2])!\n",
- => "Le minimum ([_1]) est plus grand que le maximum ([_2])!\n",
-
-Also, having valid values as keys becomes very useful if you set
-up an _AUTO lexicon. _AUTO lexicons are discussed in a later
-section.
-
-I almost always use keys that are themselves
-valid lexicon values. One notable exception is when the value is
-quite long. For example, to get the screenful of data that
-a command-line program might return when given an unknown switch,
-I often just use a brief, self-explanatory key such as "_USAGE_MESSAGE". At that point I then go
-and immediately to define that lexicon entry in the
-ProjectClass::L10N::en lexicon (since English is always my "project
-language"):
-
- '_USAGE_MESSAGE' => <<'EOSTUFF',
- ...long long message...
- EOSTUFF
-
-and then I can use it as:
-
- getopt('oDI', \%opts) or die $lh->maketext('_USAGE_MESSAGE');
-
-Incidentally,
-note that each class's C<%Lexicon> inherits-and-extends
-the lexicons in its superclasses. This is not because these are
-special hashes I<per se>, but because you access them via the
-C<maketext> method, which looks for entries across all the
-C<%Lexicon> hashes in a language class I<and> all its ancestor classes.
-(This is because the idea of "class data" isn't directly implemented
-in Perl, but is instead left to individual class-systems to implement
-as they see fit..)
-
-Note that you may have things stored in a lexicon
-besides just phrases for output: for example, if your program
-takes input from the keyboard, asking a "(Y/N)" question,
-you probably need to know what the equivalent of "Y[es]/N[o]" is
-in whatever language. You probably also need to know what
-the equivalents of the answers "y" and "n" are. You can
-store that information in the lexicon (say, under the keys
-"~answer_y" and "~answer_n", and the long forms as
-"~answer_yes" and "~answer_no", where "~" is just an ad-hoc
-character meant to indicate to programmers/translators that
-these are not phrases for output).
-
-Or instead of storing this in the language class's lexicon,
-you can (and, in some cases, really should) represent the same bit
-of knowledge as code in a method in the language class. (That
-leaves a tidy distinction between the lexicon as the things we
-know how to I<say>, and the rest of the things in the lexicon class
-as things that we know how to I<do>.) Consider
-this example of a processor for responses to French "oui/non"
-questions:
-
- sub y_or_n {
- return undef unless defined $_[1] and length $_[1];
- my $answer = lc $_[1]; # smash case
- return 1 if $answer eq 'o' or $answer eq 'oui';
- return 0 if $answer eq 'n' or $answer eq 'non';
- return undef;
- }
-
-...which you'd then call in a construct like this:
-
- my $response;
- until(defined $response) {
- print $lh->maketext("Open the pod bay door (y/n)? ");
- $response = $lh->y_or_n( get_input_from_keyboard_somehow() );
- }
- if($response) { $pod_bay_door->open() }
- else { $pod_bay_door->leave_closed() }
-
-Other data worth storing in a lexicon might be things like
-filenames for language-targetted resources:
-
- ...
- "_main_splash_png"
- => "/styles/en_us/main_splash.png",
- "_main_splash_imagemap"
- => "/styles/en_us/main_splash.incl",
- "_general_graphics_path"
- => "/styles/en_us/",
- "_alert_sound"
- => "/styles/en_us/hey_there.wav",
- "_forward_icon"
- => "left_arrow.png",
- "_backward_icon"
- => "right_arrow.png",
- # In some other languages, left equals
- # BACKwards, and right is FOREwards.
- ...
-
-You might want to do the same thing for expressing key bindings
-or the like (since hardwiring "q" as the binding for the function
-that quits a screen/menu/program is useful only if your language
-happens to associate "q" with "quit"!)
-
-=head1 BRACKET NOTATION
-
-Bracket Notation is a crucial feature of Locale::Maketext. I mean
-Bracket Notation to provide a replacement for the use of sprintf formatting.
-Everything you do with Bracket Notation could be done with a sub block,
-but bracket notation is meant to be much more concise.
-
-Bracket Notation is a like a miniature "template" system (in the sense
-of L<Text::Template|Text::Template>, not in the sense of C++ templates),
-where normal text is passed thru basically as is, but text in special
-regions is specially interpreted. In Bracket Notation, you use square brackets ("[...]"),
-not curly braces ("{...}") to note sections that are specially interpreted.
-
-For example, here all the areas that are taken literally are underlined with
-a "^", and all the in-bracket special regions are underlined with an X:
-
- "Minimum ([_1]) is larger than maximum ([_2])!\n",
- ^^^^^^^^^ XX ^^^^^^^^^^^^^^^^^^^^^^^^^^ XX ^^^^
-
-When that string is compiled from bracket notation into a real Perl sub,
-it's basically turned into:
-
- sub {
- my $lh = $_[0];
- my @params = @_;
- return join '',
- "Minimum (",
- ...some code here...
- ") is larger than maximum (",
- ...some code here...
- ")!\n",
- }
- # to be called by $lh->maketext(KEY, params...)
-
-In other words, text outside bracket groups is turned into string
-literals. Text in brackets is rather more complex, and currently follows
-these rules:
-
-=over
-
-=item *
-
-Bracket groups that are empty, or which consist only of whitespace,
-are ignored. (Examples: "[]", "[ ]", or a [ and a ] with returns
-and/or tabs and/or spaces between them.
-
-Otherwise, each group is taken to be a comma-separated group of items,
-and each item is interpreted as follows:
-
-=item *
-
-An item that is "_I<digits>" or "_-I<digits>" is interpreted as
-$_[I<value>]. I.e., "_1" becomes with $_[1], and "_-3" is interpreted
-as $_[-3] (in which case @_ should have at least three elements in it).
-Note that $_[0] is the language handle, and is typically not named
-directly.
-
-=item *
-
-An item "_*" is interpreted to mean "all of @_ except $_[0]".
-I.e., C<@_[1..$#_]>. Note that this is an empty list in the case
-of calls like $lh->maketext(I<key>) where there are no
-parameters (except $_[0], the language handle).
-
-=item *
-
-Otherwise, each item is interpreted as a string literal.
-
-=back
-
-The group as a whole is interpreted as follows:
-
-=over
-
-=item *
-
-If the first item in a bracket group looks like a method name,
-then that group is interpreted like this:
-
- $lh->that_method_name(
- ...rest of items in this group...
- ),
-
-=item *
-
-If the first item in a bracket group is "*", it's taken as shorthand
-for the so commonly called "quant" method. Similarly, if the first
-item in a bracket group is "#", it's taken to be shorthand for
-"numf".
-
-=item *
-
-If the first item in a bracket group is the empty-string, or "_*"
-or "_I<digits>" or "_-I<digits>", then that group is interpreted
-as just the interpolation of all its items:
-
- join('',
- ...rest of items in this group...
- ),
-
-Examples: "[_1]" and "[,_1]", which are synonymous; and
-"C<[,ID-(,_4,-,_2,)]>", which compiles as
-C<join "", "ID-(", $_[4], "-", $_[2], ")">.
-
-=item *
-
-Otherwise this bracket group is invalid. For example, in the group
-"[!@#,whatever]", the first item C<"!@#"> is neither the empty-string,
-"_I<number>", "_-I<number>", "_*", nor a valid method name; and so
-Locale::Maketext will throw an exception of you try compiling an
-expression containing this bracket group.
-
-=back
-
-Note, incidentally, that items in each group are comma-separated,
-not C</\s*,\s*/>-separated. That is, you might expect that this
-bracket group:
-
- "Hoohah [foo, _1 , bar ,baz]!"
-
-would compile to this:
-
- sub {
- my $lh = $_[0];
- return join '',
- "Hoohah ",
- $lh->foo( $_[1], "bar", "baz"),
- "!",
- }
-
-But it actually compiles as this:
-
- sub {
- my $lh = $_[0];
- return join '',
- "Hoohah ",
- $lh->foo(" _1 ", " bar ", "baz"), # note the <space> in " bar "
- "!",
- }
-
-In the notation discussed so far, the characters "[" and "]" are given
-special meaning, for opening and closing bracket groups, and "," has
-a special meaning inside bracket groups, where it separates items in the
-group. This begs the question of how you'd express a literal "[" or
-"]" in a Bracket Notation string, and how you'd express a literal
-comma inside a bracket group. For this purpose I've adopted "~" (tilde)
-as an escape character: "~[" means a literal '[' character anywhere
-in Bracket Notation (i.e., regardless of whether you're in a bracket
-group or not), and ditto for "~]" meaning a literal ']', and "~," meaning
-a literal comma. (Altho "," means a literal comma outside of
-bracket groups -- it's only inside bracket groups that commas are special.)
-
-And on the off chance you need a literal tilde in a bracket expression,
-you get it with "~~".
-
-Currently, an unescaped "~" before a character
-other than a bracket or a comma is taken to mean just a "~" and that
-character. I.e., "~X" means the same as "~~X" -- i.e., one literal tilde,
-and then one literal "X". However, by using "~X", you are assuming that
-no future version of Maketext will use "~X" as a magic escape sequence.
-In practice this is not a great problem, since first off you can just
-write "~~X" and not worry about it; second off, I doubt I'll add lots
-of new magic characters to bracket notation; and third off, you
-aren't likely to want literal "~" characters in your messages anyway,
-since it's not a character with wide use in natural language text.
-
-Brackets must be balanced -- every openbracket must have
-one matching closebracket, and vice versa. So these are all B<invalid>:
-
- "I ate [quant,_1,rhubarb pie."
- "I ate [quant,_1,rhubarb pie[."
- "I ate quant,_1,rhubarb pie]."
- "I ate quant,_1,rhubarb pie[."
-
-Currently, bracket groups do not nest. That is, you B<cannot> say:
-
- "Foo [bar,baz,[quux,quuux]]\n";
-
-If you need a notation that's that powerful, use normal Perl:
-
- %Lexicon = (
- ...
- "some_key" => sub {
- my $lh = $_[0];
- join '',
- "Foo ",
- $lh->bar('baz', $lh->quux('quuux')),
- "\n",
- },
- ...
- );
-
-Or write the "bar" method so you don't need to pass it the
-output from calling quux.
-
-I do not anticipate that you will need (or particularly want)
-to nest bracket groups, but you are welcome to email me with
-convincing (real-life) arguments to the contrary.
-
-=head1 AUTO LEXICONS
-
-If maketext goes to look in an individual %Lexicon for an entry
-for I<key> (where I<key> does not start with an underscore), and
-sees none, B<but does see> an entry of "_AUTO" => I<some_true_value>,
-then we actually define $Lexicon{I<key>} = I<key> right then and there,
-and then use that value as if it had been there all
-along. This happens before we even look in any superclass %Lexicons!
-
-(This is meant to be somewhat like the AUTOLOAD mechanism in
-Perl's function call system -- or, looked at another way,
-like the L<AutoLoader|AutoLoader> module.)
-
-I can picture all sorts of circumstances where you just
-do not want lookup to be able to fail (since failing
-normally means that maketext throws a C<die>, although
-see the next section for greater control over that). But
-here's one circumstance where _AUTO lexicons are meant to
-be I<especially> useful:
-
-As you're writing an application, you decide as you go what messages
-you need to emit. Normally you'd go to write this:
-
- if(-e $filename) {
- go_process_file($filename)
- } else {
- print qq{Couldn't find file "$filename"!\n};
- }
-
-but since you anticipate localizing this, you write:
-
- use ThisProject::I18N;
- my $lh = ThisProject::I18N->get_handle();
- # For the moment, assume that things are set up so
- # that we load class ThisProject::I18N::en
- # and that that's the class that $lh belongs to.
- ...
- if(-e $filename) {
- go_process_file($filename)
- } else {
- print $lh->maketext(
- qq{Couldn't find file "[_1]"!\n}, $filename
- );
- }
-
-Now, right after you've just written the above lines, you'd
-normally have to go open the file
-ThisProject/I18N/en.pm, and immediately add an entry:
-
- "Couldn't find file \"[_1]\"!\n"
- => "Couldn't find file \"[_1]\"!\n",
-
-But I consider that somewhat of a distraction from the work
-of getting the main code working -- to say nothing of the fact
-that I often have to play with the program a few times before
-I can decide exactly what wording I want in the messages (which
-in this case would require me to go changing three lines of code:
-the call to maketext with that key, and then the two lines in
-ThisProject/I18N/en.pm).
-
-However, if you set "_AUTO => 1" in the %Lexicon in,
-ThisProject/I18N/en.pm (assuming that English (en) is
-the language that all your programmers will be using for this
-project's internal message keys), then you don't ever have to
-go adding lines like this
-
- "Couldn't find file \"[_1]\"!\n"
- => "Couldn't find file \"[_1]\"!\n",
-
-to ThisProject/I18N/en.pm, because if _AUTO is true there,
-then just looking for an entry with the key "Couldn't find
-file \"[_1]\"!\n" in that lexicon will cause it to be added,
-with that value!
-
-Note that the reason that keys that start with "_"
-are immune to _AUTO isn't anything generally magical about
-the underscore character -- I just wanted a way to have most
-lexicon keys be autoable, except for possibly a few, and I
-arbitrarily decided to use a leading underscore as a signal
-to distinguish those few.
-
-=head1 READONLY LEXICONS
-
-If your lexicon is a tied hash the simple act of caching the compiled value can be fatal.
-
-For example a L<GDBM_File> GDBM_READER tied hash will die with something like:
-
- gdbm store returned -1, errno 2, key "..." at ...
-
-All you need to do is turn on caching outside of the lexicon hash itself like so:
-
- sub init {
- my ($lh) = @_;
- ...
- $lh->{'use_external_lex_cache'} = 1;
- ...
- }
-
-And then instead of storing the compiled value in the lexicon hash it will store it in $lh->{'_external_lex_cache'}
-
-=head1 CONTROLLING LOOKUP FAILURE
-
-If you call $lh->maketext(I<key>, ...parameters...),
-and there's no entry I<key> in $lh's class's %Lexicon, nor
-in the superclass %Lexicon hash, I<and> if we can't auto-make
-I<key> (because either it starts with a "_", or because none
-of its lexicons have C<_AUTO =E<gt> 1,>), then we have
-failed to find a normal way to maketext I<key>. What then
-happens in these failure conditions, depends on the $lh object's
-"fail" attribute.
-
-If the language handle has no "fail" attribute, maketext
-will simply throw an exception (i.e., it calls C<die>, mentioning
-the I<key> whose lookup failed, and naming the line number where
-the calling $lh->maketext(I<key>,...) was.
-
-If the language handle has a "fail" attribute whose value is a
-coderef, then $lh->maketext(I<key>,...params...) gives up and calls:
-
- return $that_subref->($lh, $key, @params);
-
-Otherwise, the "fail" attribute's value should be a string denoting
-a method name, so that $lh->maketext(I<key>,...params...) can
-give up with:
-
- return $lh->$that_method_name($phrase, @params);
-
-The "fail" attribute can be accessed with the C<fail_with> method:
-
- # Set to a coderef:
- $lh->fail_with( \&failure_handler );
-
- # Set to a method name:
- $lh->fail_with( 'failure_method' );
-
- # Set to nothing (i.e., so failure throws a plain exception)
- $lh->fail_with( undef );
-
- # Get the current value
- $handler = $lh->fail_with();
-
-Now, as to what you may want to do with these handlers: Maybe you'd
-want to log what key failed for what class, and then die. Maybe
-you don't like C<die> and instead you want to send the error message
-to STDOUT (or wherever) and then merely C<exit()>.
-
-Or maybe you don't want to C<die> at all! Maybe you could use a
-handler like this:
-
- # Make all lookups fall back onto an English value,
- # but only after we log it for later fingerpointing.
- my $lh_backup = ThisProject->get_handle('en');
- open(LEX_FAIL_LOG, ">>wherever/lex.log") || die "GNAARGH $!";
- sub lex_fail {
- my($failing_lh, $key, $params) = @_;
- print LEX_FAIL_LOG scalar(localtime), "\t",
- ref($failing_lh), "\t", $key, "\n";
- return $lh_backup->maketext($key,@params);
- }
-
-Some users have expressed that they think this whole mechanism of
-having a "fail" attribute at all, seems a rather pointless complication.
-But I want Locale::Maketext to be usable for software projects of I<any>
-scale and type; and different software projects have different ideas
-of what the right thing is to do in failure conditions. I could simply
-say that failure always throws an exception, and that if you want to be
-careful, you'll just have to wrap every call to $lh->maketext in an
-S<eval { }>. However, I want programmers to reserve the right (via
-the "fail" attribute) to treat lookup failure as something other than
-an exception of the same level of severity as a config file being
-unreadable, or some essential resource being inaccessible.
-
-One possibly useful value for the "fail" attribute is the method name
-"failure_handler_auto". This is a method defined in the class
-Locale::Maketext itself. You set it with:
-
- $lh->fail_with('failure_handler_auto');
-
-Then when you call $lh->maketext(I<key>, ...parameters...) and
-there's no I<key> in any of those lexicons, maketext gives up with
-
- return $lh->failure_handler_auto($key, @params);
-
-But failure_handler_auto, instead of dying or anything, compiles
-$key, caching it in
-
- $lh->{'failure_lex'}{$key} = $complied
-
-and then calls the compiled value, and returns that. (I.e., if
-$key looks like bracket notation, $compiled is a sub, and we return
-&{$compiled}(@params); but if $key is just a plain string, we just
-return that.)
-
-The effect of using "failure_auto_handler"
-is like an AUTO lexicon, except that it 1) compiles $key even if
-it starts with "_", and 2) you have a record in the new hashref
-$lh->{'failure_lex'} of all the keys that have failed for
-this object. This should avoid your program dying -- as long
-as your keys aren't actually invalid as bracket code, and as
-long as they don't try calling methods that don't exist.
-
-"failure_auto_handler" may not be exactly what you want, but I
-hope it at least shows you that maketext failure can be mitigated
-in any number of very flexible ways. If you can formalize exactly
-what you want, you should be able to express that as a failure
-handler. You can even make it default for every object of a given
-class, by setting it in that class's init:
-
- sub init {
- my $lh = $_[0]; # a newborn handle
- $lh->SUPER::init();
- $lh->fail_with('my_clever_failure_handler');
- return;
- }
- sub my_clever_failure_handler {
- ...you clever things here...
- }
-
-=head1 HOW TO USE MAKETEXT
-
-Here is a brief checklist on how to use Maketext to localize
-applications:
-
-=over
-
-=item *
-
-Decide what system you'll use for lexicon keys. If you insist,
-you can use opaque IDs (if you're nostalgic for C<catgets>),
-but I have better suggestions in the
-section "Entries in Each Lexicon", above. Assuming you opt for
-meaningful keys that double as values (like "Minimum ([_1]) is
-larger than maximum ([_2])!\n"), you'll have to settle on what
-language those should be in. For the sake of argument, I'll
-call this English, specifically American English, "en-US".
-
-=item *
-
-Create a class for your localization project. This is
-the name of the class that you'll use in the idiom:
-
- use Projname::L10N;
- my $lh = Projname::L10N->get_handle(...) || die "Language?";
-
-Assuming you call your class Projname::L10N, create a class
-consisting minimally of:
-
- package Projname::L10N;
- use base qw(Locale::Maketext);
- ...any methods you might want all your languages to share...
-
- # And, assuming you want the base class to be an _AUTO lexicon,
- # as is discussed a few sections up:
-
- 1;
-
-=item *
-
-Create a class for the language your internal keys are in. Name
-the class after the language-tag for that language, in lowercase,
-with dashes changed to underscores. Assuming your project's first
-language is US English, you should call this Projname::L10N::en_us.
-It should consist minimally of:
-
- package Projname::L10N::en_us;
- use base qw(Projname::L10N);
- %Lexicon = (
- '_AUTO' => 1,
- );
- 1;
-
-(For the rest of this section, I'll assume that this "first
-language class" of Projname::L10N::en_us has
-_AUTO lexicon.)
-
-=item *
-
-Go and write your program. Everywhere in your program where
-you would say:
-
- print "Foobar $thing stuff\n";
-
-instead do it thru maketext, using no variable interpolation in
-the key:
-
- print $lh->maketext("Foobar [_1] stuff\n", $thing);
-
-If you get tired of constantly saying C<print $lh-E<gt>maketext>,
-consider making a functional wrapper for it, like so:
-
- use Projname::L10N;
- use vars qw($lh);
- $lh = Projname::L10N->get_handle(...) || die "Language?";
- sub pmt (@) { print( $lh->maketext(@_)) }
- # "pmt" is short for "Print MakeText"
- $Carp::Verbose = 1;
- # so if maketext fails, we see made the call to pmt
-
-Besides whole phrases meant for output, anything language-dependent
-should be put into the class Projname::L10N::en_us,
-whether as methods, or as lexicon entries -- this is discussed
-in the section "Entries in Each Lexicon", above.
-
-=item *
-
-Once the program is otherwise done, and once its localization for
-the first language works right (via the data and methods in
-Projname::L10N::en_us), you can get together the data for translation.
-If your first language lexicon isn't an _AUTO lexicon, then you already
-have all the messages explicitly in the lexicon (or else you'd be
-getting exceptions thrown when you call $lh->maketext to get
-messages that aren't in there). But if you were (advisedly) lazy and are
-using an _AUTO lexicon, then you've got to make a list of all the phrases
-that you've so far been letting _AUTO generate for you. There are very
-many ways to assemble such a list. The most straightforward is to simply
-grep the source for every occurrence of "maketext" (or calls
-to wrappers around it, like the above C<pmt> function), and to log the
-following phrase.
-
-=item *
-
-You may at this point want to consider whether your base class
-(Projname::L10N), from which all lexicons inherit from (Projname::L10N::en,
-Projname::L10N::es, etc.), should be an _AUTO lexicon. It may be true
-that in theory, all needed messages will be in each language class;
-but in the presumably unlikely or "impossible" case of lookup failure,
-you should consider whether your program should throw an exception,
-emit text in English (or whatever your project's first language is),
-or some more complex solution as described in the section
-"Controlling Lookup Failure", above.
-
-=item *
-
-Submit all messages/phrases/etc. to translators.
-
-(You may, in fact, want to start with localizing to I<one> other language
-at first, if you're not sure that you've properly abstracted the
-language-dependent parts of your code.)
-
-Translators may request clarification of the situation in which a
-particular phrase is found. For example, in English we are entirely happy
-saying "I<n> files found", regardless of whether we mean "I looked for files,
-and found I<n> of them" or the rather distinct situation of "I looked for
-something else (like lines in files), and along the way I saw I<n>
-files." This may involve rethinking things that you thought quite clear:
-should "Edit" on a toolbar be a noun ("editing") or a verb ("to edit")? Is
-there already a conventionalized way to express that menu option, separate
-from the target language's normal word for "to edit"?
-
-In all cases where the very common phenomenon of quantification
-(saying "I<N> files", for B<any> value of N)
-is involved, each translator should make clear what dependencies the
-number causes in the sentence. In many cases, dependency is
-limited to words adjacent to the number, in places where you might
-expect them ("I found the-?PLURAL I<N>
-empty-?PLURAL directory-?PLURAL"), but in some cases there are
-unexpected dependencies ("I found-?PLURAL ..."!) as well as long-distance
-dependencies "The I<N> directory-?PLURAL could not be deleted-?PLURAL"!).
-
-Remind the translators to consider the case where N is 0:
-"0 files found" isn't exactly natural-sounding in any language, but it
-may be unacceptable in many -- or it may condition special
-kinds of agreement (similar to English "I didN'T find ANY files").
-
-Remember to ask your translators about numeral formatting in their
-language, so that you can override the C<numf> method as
-appropriate. Typical variables in number formatting are: what to
-use as a decimal point (comma? period?); what to use as a thousands
-separator (space? nonbreaking space? comma? period? small
-middot? prime? apostrophe?); and even whether the so-called "thousands
-separator" is actually for every third digit -- I've heard reports of
-two hundred thousand being expressible as "2,00,000" for some Indian
-(Subcontinental) languages, besides the less surprising "S<200 000>",
-"200.000", "200,000", and "200'000". Also, using a set of numeral
-glyphs other than the usual ASCII "0"-"9" might be appreciated, as via
-C<tr/0-9/\x{0966}-\x{096F}/> for getting digits in Devanagari script
-(for Hindi, Konkani, others).
-
-The basic C<quant> method that Locale::Maketext provides should be
-good for many languages. For some languages, it might be useful
-to modify it (or its constituent C<numerate> method)
-to take a plural form in the two-argument call to C<quant>
-(as in "[quant,_1,files]") if
-it's all-around easier to infer the singular form from the plural, than
-to infer the plural form from the singular.
-
-But for other languages (as is discussed at length
-in L<Locale::Maketext::TPJ13|Locale::Maketext::TPJ13>), simple
-C<quant>/C<numf> is not enough. For the particularly problematic
-Slavic languages, what you may need is a method which you provide
-with the number, the citation form of the noun to quantify, and
-the case and gender that the sentence's syntax projects onto that
-noun slot. The method would then be responsible for determining
-what grammatical number that numeral projects onto its noun phrase,
-and what case and gender it may override the normal case and gender
-with; and then it would look up the noun in a lexicon providing
-all needed inflected forms.
-
-=item *
-
-You may also wish to discuss with the translators the question of
-how to relate different subforms of the same language tag,
-considering how this reacts with C<get_handle>'s treatment of
-these. For example, if a user accepts interfaces in "en, fr", and
-you have interfaces available in "en-US" and "fr", what should
-they get? You may wish to resolve this by establishing that "en"
-and "en-US" are effectively synonymous, by having one class
-zero-derive from the other.
-
-For some languages this issue may never come up (Danish is rarely
-expressed as "da-DK", but instead is just "da"). And for other
-languages, the whole concept of a "generic" form may verge on
-being uselessly vague, particularly for interfaces involving voice
-media in forms of Arabic or Chinese.
-
-=item *
-
-Once you've localized your program/site/etc. for all desired
-languages, be sure to show the result (whether live, or via
-screenshots) to the translators. Once they approve, make every
-effort to have it then checked by at least one other speaker of
-that language. This holds true even when (or especially when) the
-translation is done by one of your own programmers. Some
-kinds of systems may be harder to find testers for than others,
-depending on the amount of domain-specific jargon and concepts
-involved -- it's easier to find people who can tell you whether
-they approve of your translation for "delete this message" in an
-email-via-Web interface, than to find people who can give you
-an informed opinion on your translation for "attribute value"
-in an XML query tool's interface.
-
-=back
-
-=head1 SEE ALSO
-
-I recommend reading all of these:
-
-L<Locale::Maketext::TPJ13|Locale::Maketext::TPJ13> -- my I<The Perl
-Journal> article about Maketext. It explains many important concepts
-underlying Locale::Maketext's design, and some insight into why
-Maketext is better than the plain old approach of having
-message catalogs that are just databases of sprintf formats.
-
-L<File::Findgrep|File::Findgrep> is a sample application/module
-that uses Locale::Maketext to localize its messages. For a larger
-internationalized system, see also L<Apache::MP3>.
-
-L<I18N::LangTags|I18N::LangTags>.
-
-L<Win32::Locale|Win32::Locale>.
-
-RFC 3066, I<Tags for the Identification of Languages>,
-as at http://sunsite.dk/RFC/rfc/rfc3066.html
-
-RFC 2277, I<IETF Policy on Character Sets and Languages>
-is at http://sunsite.dk/RFC/rfc/rfc2277.html -- much of it is
-just things of interest to protocol designers, but it explains
-some basic concepts, like the distinction between locales and
-language-tags.
-
-The manual for GNU C<gettext>. The gettext dist is available in
-C<ftp://prep.ai.mit.edu/pub/gnu/> -- get
-a recent gettext tarball and look in its "doc/" directory, there's
-an easily browsable HTML version in there. The
-gettext documentation asks lots of questions worth thinking
-about, even if some of their answers are sometimes wonky,
-particularly where they start talking about pluralization.
-
-The Locale/Maketext.pm source. Obverse that the module is much
-shorter than its documentation!
-
-=head1 COPYRIGHT AND DISCLAIMER
-
-Copyright (c) 1999-2004 Sean M. Burke. All rights reserved.
-
-This library is free software; you can redistribute it and/or modify
-it under the same terms as Perl itself.
-
-This program is distributed in the hope that it will be useful, but
-without any warranty; without even the implied warranty of
-merchantability or fitness for a particular purpose.
-
-=head1 AUTHOR
-
-Sean M. Burke C<sburke@cpan.org>
-
-=cut