1425 lines
51 KiB
Plaintext
1425 lines
51 KiB
Plaintext
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# Time-stamp: "2004-01-11 18:35:34 AST"
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=head1 NAME
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Locale::Maketext - framework for localization
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=head1 SYNOPSIS
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package MyProgram;
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use strict;
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use MyProgram::L10N;
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# ...which inherits from Locale::Maketext
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my $lh = MyProgram::L10N->get_handle() || die "What language?";
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...
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# And then any messages your program emits, like:
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warn $lh->maketext( "Can't open file [_1]: [_2]\n", $f, $! );
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...
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=head1 DESCRIPTION
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It is a common feature of applications (whether run directly,
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or via the Web) for them to be "localized" -- i.e., for them
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to a present an English interface to an English-speaker, a German
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interface to a German-speaker, and so on for all languages it's
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programmed with. Locale::Maketext
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is a framework for software localization; it provides you with the
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tools for organizing and accessing the bits of text and text-processing
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code that you need for producing localized applications.
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In order to make sense of Maketext and how all its
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components fit together, you should probably
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go read L<Locale::Maketext::TPJ13|Locale::Maketext::TPJ13>, and
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I<then> read the following documentation.
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You may also want to read over the source for C<File::Findgrep>
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and its constituent modules -- they are a complete (if small)
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example application that uses Maketext.
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=head1 QUICK OVERVIEW
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The basic design of Locale::Maketext is object-oriented, and
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Locale::Maketext is an abstract base class, from which you
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derive a "project class".
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The project class (with a name like "TkBocciBall::Localize",
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which you then use in your module) is in turn the base class
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for all the "language classes" for your project
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(with names "TkBocciBall::Localize::it",
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"TkBocciBall::Localize::en",
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"TkBocciBall::Localize::fr", etc.).
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A language class is
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a class containing a lexicon of phrases as class data,
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and possibly also some methods that are of use in interpreting
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phrases in the lexicon, or otherwise dealing with text in that
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language.
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An object belonging to a language class is called a "language
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handle"; it's typically a flyweight object.
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The normal course of action is to call:
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use TkBocciBall::Localize; # the localization project class
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$lh = TkBocciBall::Localize->get_handle();
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# Depending on the user's locale, etc., this will
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# make a language handle from among the classes available,
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# and any defaults that you declare.
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die "Couldn't make a language handle??" unless $lh;
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From then on, you use the C<maketext> function to access
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entries in whatever lexicon(s) belong to the language handle
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you got. So, this:
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print $lh->maketext("You won!"), "\n";
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...emits the right text for this language. If the object
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in C<$lh> belongs to class "TkBocciBall::Localize::fr" and
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%TkBocciBall::Localize::fr::Lexicon contains C<("You won!"
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=E<gt> "Tu as gagnE<eacute>!")>, then the above
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code happily tells the user "Tu as gagnE<eacute>!".
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=head1 METHODS
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Locale::Maketext offers a variety of methods, which fall
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into three categories:
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=over
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=item *
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Methods to do with constructing language handles.
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=item *
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C<maketext> and other methods to do with accessing %Lexicon data
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for a given language handle.
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=item *
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Methods that you may find it handy to use, from routines of
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yours that you put in %Lexicon entries.
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=back
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These are covered in the following section.
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=head2 Construction Methods
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These are to do with constructing a language handle:
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=over
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=item *
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$lh = YourProjClass->get_handle( ...langtags... ) || die "lg-handle?";
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This tries loading classes based on the language-tags you give (like
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C<("en-US", "sk", "kon", "es-MX", "ja", "i-klingon")>, and for the first class
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that succeeds, returns YourProjClass::I<language>->new().
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If it runs thru the entire given list of language-tags, and finds no classes
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for those exact terms, it then tries "superordinate" language classes.
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So if no "en-US" class (i.e., YourProjClass::en_us)
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was found, nor classes for anything else in that list, we then try
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its superordinate, "en" (i.e., YourProjClass::en), and so on thru
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the other language-tags in the given list: "es".
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(The other language-tags in our example list:
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happen to have no superordinates.)
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If none of those language-tags leads to loadable classes, we then
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try classes derived from YourProjClass->fallback_languages() and
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then if nothing comes of that, we use classes named by
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YourProjClass->fallback_language_classes(). Then in the (probably
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quite unlikely) event that that fails, we just return undef.
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=item *
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$lh = YourProjClass->get_handleB<()> || die "lg-handle?";
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When C<get_handle> is called with an empty parameter list, magic happens:
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If C<get_handle> senses that it's running in program that was
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invoked as a CGI, then it tries to get language-tags out of the
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environment variable "HTTP_ACCEPT_LANGUAGE", and it pretends that
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those were the languages passed as parameters to C<get_handle>.
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Otherwise (i.e., if not a CGI), this tries various OS-specific ways
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to get the language-tags for the current locale/language, and then
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pretends that those were the value(s) passed to C<get_handle>.
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Currently this OS-specific stuff consists of looking in the environment
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variables "LANG" and "LANGUAGE"; and on MSWin machines (where those
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variables are typically unused), this also tries using
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the module Win32::Locale to get a language-tag for whatever language/locale
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is currently selected in the "Regional Settings" (or "International"?)
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Control Panel. I welcome further
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suggestions for making this do the Right Thing under other operating
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systems that support localization.
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If you're using localization in an application that keeps a configuration
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file, you might consider something like this in your project class:
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sub get_handle_via_config {
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my $class = $_[0];
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my $chosen_language = $Config_settings{'language'};
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my $lh;
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if($chosen_language) {
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$lh = $class->get_handle($chosen_language)
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|| die "No language handle for \"$chosen_language\""
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. " or the like";
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} else {
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# Config file missing, maybe?
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$lh = $class->get_handle()
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|| die "Can't get a language handle";
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}
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return $lh;
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}
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=item *
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$lh = YourProjClass::langname->new();
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This constructs a language handle. You usually B<don't> call this
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directly, but instead let C<get_handle> find a language class to C<use>
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and to then call ->new on.
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=item *
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$lh->init();
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This is called by ->new to initialize newly-constructed language handles.
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If you define an init method in your class, remember that it's usually
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considered a good idea to call $lh->SUPER::init in it (presumably at the
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beginning), so that all classes get a chance to initialize a new object
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however they see fit.
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=item *
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YourProjClass->fallback_languages()
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C<get_handle> appends the return value of this to the end of
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whatever list of languages you pass C<get_handle>. Unless
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you override this method, your project class
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will inherit Locale::Maketext's C<fallback_languages>, which
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currently returns C<('i-default', 'en', 'en-US')>.
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("i-default" is defined in RFC 2277).
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This method (by having it return the name
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of a language-tag that has an existing language class)
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can be used for making sure that
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C<get_handle> will always manage to construct a language
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handle (assuming your language classes are in an appropriate
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@INC directory). Or you can use the next method:
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=item *
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YourProjClass->fallback_language_classes()
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C<get_handle> appends the return value of this to the end
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of the list of classes it will try using. Unless
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you override this method, your project class
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will inherit Locale::Maketext's C<fallback_language_classes>,
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which currently returns an empty list, C<()>.
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By setting this to some value (namely, the name of a loadable
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language class), you can be sure that
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C<get_handle> will always manage to construct a language
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handle.
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=back
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=head2 The "maketext" Method
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This is the most important method in Locale::Maketext:
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$text = $lh->maketext(I<key>, ...parameters for this phrase...);
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This looks in the %Lexicon of the language handle
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$lh and all its superclasses, looking
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for an entry whose key is the string I<key>. Assuming such
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an entry is found, various things then happen, depending on the
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value found:
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If the value is a scalarref, the scalar is dereferenced and returned
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(and any parameters are ignored).
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If the value is a coderef, we return &$value($lh, ...parameters...).
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If the value is a string that I<doesn't> look like it's in Bracket Notation,
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we return it (after replacing it with a scalarref, in its %Lexicon).
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If the value I<does> look like it's in Bracket Notation, then we compile
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it into a sub, replace the string in the %Lexicon with the new coderef,
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and then we return &$new_sub($lh, ...parameters...).
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Bracket Notation is discussed in a later section. Note
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that trying to compile a string into Bracket Notation can throw
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an exception if the string is not syntactically valid (say, by not
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balancing brackets right.)
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Also, calling &$coderef($lh, ...parameters...) can throw any sort of
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exception (if, say, code in that sub tries to divide by zero). But
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a very common exception occurs when you have Bracket
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Notation text that says to call a method "foo", but there is no such
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method. (E.g., "You have [quaB<tn>,_1,ball]." will throw an exception
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on trying to call $lh->quaB<tn>($_[1],'ball') -- you presumably meant
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"quant".) C<maketext> catches these exceptions, but only to make the
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error message more readable, at which point it rethrows the exception.
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An exception I<may> be thrown if I<key> is not found in any
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of $lh's %Lexicon hashes. What happens if a key is not found,
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is discussed in a later section, "Controlling Lookup Failure".
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Note that you might find it useful in some cases to override
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the C<maketext> method with an "after method", if you want to
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translate encodings, or even scripts:
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package YrProj::zh_cn; # Chinese with PRC-style glyphs
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use base ('YrProj::zh_tw'); # Taiwan-style
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sub maketext {
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my $self = shift(@_);
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my $value = $self->maketext(@_);
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return Chineeze::taiwan2mainland($value);
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}
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Or you may want to override it with something that traps
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any exceptions, if that's critical to your program:
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sub maketext {
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my($lh, @stuff) = @_;
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my $out;
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eval { $out = $lh->SUPER::maketext(@stuff) };
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return $out unless $@;
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...otherwise deal with the exception...
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}
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Other than those two situations, I don't imagine that
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it's useful to override the C<maketext> method. (If
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you run into a situation where it is useful, I'd be
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interested in hearing about it.)
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=over
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=item $lh->fail_with I<or> $lh->fail_with(I<PARAM>)
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=item $lh->failure_handler_auto
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These two methods are discussed in the section "Controlling
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Lookup Failure".
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=item $lh->blacklist(@list)
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=item $lh->whitelist(@list)
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These methods are discussed in the section "Bracket Notation
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Security".
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=back
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=head2 Utility Methods
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These are methods that you may find it handy to use, generally
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from %Lexicon routines of yours (whether expressed as
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Bracket Notation or not).
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=over
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=item $language->quant($number, $singular)
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=item $language->quant($number, $singular, $plural)
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=item $language->quant($number, $singular, $plural, $negative)
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This is generally meant to be called from inside Bracket Notation
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(which is discussed later), as in
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"Your search matched [quant,_1,document]!"
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It's for I<quantifying> a noun (i.e., saying how much of it there is,
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while giving the correct form of it). The behavior of this method is
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handy for English and a few other Western European languages, and you
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should override it for languages where it's not suitable. You can feel
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free to read the source, but the current implementation is basically
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as this pseudocode describes:
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if $number is 0 and there's a $negative,
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return $negative;
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elsif $number is 1,
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return "1 $singular";
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elsif there's a $plural,
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return "$number $plural";
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else
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return "$number " . $singular . "s";
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#
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# ...except that we actually call numf to
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# stringify $number before returning it.
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So for English (with Bracket Notation)
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C<"...[quant,_1,file]..."> is fine (for 0 it returns "0 files",
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for 1 it returns "1 file", and for more it returns "2 files", etc.)
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But for "directory", you'd want C<"[quant,_1,directory,directories]">
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so that our elementary C<quant> method doesn't think that the
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plural of "directory" is "directorys". And you might find that the
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output may sound better if you specify a negative form, as in:
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"[quant,_1,file,files,No files] matched your query.\n"
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Remember to keep in mind verb agreement (or adjectives too, in
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other languages), as in:
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"[quant,_1,document] were matched.\n"
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Because if _1 is one, you get "1 document B<were> matched".
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An acceptable hack here is to do something like this:
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"[quant,_1,document was, documents were] matched.\n"
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=item $language->numf($number)
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This returns the given number formatted nicely according to
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this language's conventions. Maketext's default method is
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mostly to just take the normal string form of the number
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(applying sprintf "%G" for only very large numbers), and then
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to add commas as necessary. (Except that
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we apply C<tr/,./.,/> if $language->{'numf_comma'} is true;
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that's a bit of a hack that's useful for languages that express
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two million as "2.000.000" and not as "2,000,000").
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If you want anything fancier, consider overriding this with something
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that uses L<Number::Format|Number::Format>, or does something else
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entirely.
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Note that numf is called by quant for stringifying all quantifying
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numbers.
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=item $language->numerate($number, $singular, $plural, $negative)
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This returns the given noun form which is appropriate for the quantity
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C<$number> according to this language's conventions. C<numerate> is
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used internally by C<quant> to quantify nouns. Use it directly --
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usually from bracket notation -- to avoid C<quant>'s implicit call to
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C<numf> and output of a numeric quantity.
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=item $language->sprintf($format, @items)
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This is just a wrapper around Perl's normal C<sprintf> function.
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It's provided so that you can use "sprintf" in Bracket Notation:
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"Couldn't access datanode [sprintf,%10x=~[%s~],_1,_2]!\n"
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returning...
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Couldn't access datanode Stuff=[thangamabob]!
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=item $language->language_tag()
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Currently this just takes the last bit of C<ref($language)>, turns
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underscores to dashes, and returns it. So if $language is
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an object of class Hee::HOO::Haw::en_us, $language->language_tag()
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returns "en-us". (Yes, the usual representation for that language
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tag is "en-US", but case is I<never> considered meaningful in
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language-tag comparison.)
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You may override this as you like; Maketext doesn't use it for
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anything.
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=item $language->encoding()
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Currently this isn't used for anything, but it's provided
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(with default value of
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C<(ref($language) && $language-E<gt>{'encoding'})) or "iso-8859-1">
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) as a sort of suggestion that it may be useful/necessary to
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associate encodings with your language handles (whether on a
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per-class or even per-handle basis.)
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=back
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=head2 Language Handle Attributes and Internals
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A language handle is a flyweight object -- i.e., it doesn't (necessarily)
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carry any data of interest, other than just being a member of
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whatever class it belongs to.
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A language handle is implemented as a blessed hash. Subclasses of yours
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can store whatever data you want in the hash. Currently the only hash
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entry used by any crucial Maketext method is "fail", so feel free to
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use anything else as you like.
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B<Remember: Don't be afraid to read the Maketext source if there's
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any point on which this documentation is unclear.> This documentation
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is vastly longer than the module source itself.
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=head1 LANGUAGE CLASS HIERARCHIES
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These are Locale::Maketext's assumptions about the class
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hierarchy formed by all your language classes:
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=over
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=item *
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You must have a project base class, which you load, and
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which you then use as the first argument in
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the call to YourProjClass->get_handle(...). It should derive
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(whether directly or indirectly) from Locale::Maketext.
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It B<doesn't matter> how you name this class, although assuming this
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is the localization component of your Super Mega Program,
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good names for your project class might be
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SuperMegaProgram::Localization, SuperMegaProgram::L10N,
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SuperMegaProgram::I18N, SuperMegaProgram::International,
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or even SuperMegaProgram::Languages or SuperMegaProgram::Messages.
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=item *
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Language classes are what YourProjClass->get_handle will try to load.
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It will look for them by taking each language-tag (B<skipping> it
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if it doesn't look like a language-tag or locale-tag!), turning it to
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all lowercase, turning dashes to underscores, and appending it
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to YourProjClass . "::". So this:
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$lh = YourProjClass->get_handle(
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'en-US', 'fr', 'kon', 'i-klingon', 'i-klingon-romanized'
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);
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will try loading the classes
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YourProjClass::en_us (note lowercase!), YourProjClass::fr,
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YourProjClass::kon,
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YourProjClass::i_klingon
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and YourProjClass::i_klingon_romanized. (And it'll stop at the
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first one that actually loads.)
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=item *
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I assume that each language class derives (directly or indirectly)
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from your project class, and also defines its @ISA, its %Lexicon,
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or both. But I anticipate no dire consequences if these assumptions
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do not hold.
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|
=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 BRACKET NOTATION SECURITY
|
|
|
|
Locale::Maketext does not use any special syntax to differentiate
|
|
bracket notation methods from normal class or object methods. This
|
|
design makes it vulnerable to format string attacks whenever it is
|
|
used to process strings provided by untrusted users.
|
|
|
|
Locale::Maketext does support blacklist and whitelist functionality
|
|
to limit which methods may be called as bracket notation methods.
|
|
|
|
By default, Locale::Maketext blacklists all methods in the
|
|
Locale::Maketext namespace that begin with the '_' character,
|
|
and all methods which include Perl's namespace separator characters.
|
|
|
|
The default blacklist for Locale::Maketext also prevents use of the
|
|
following methods in bracket notation:
|
|
|
|
blacklist
|
|
encoding
|
|
fail_with
|
|
failure_handler_auto
|
|
fallback_language_classes
|
|
fallback_languages
|
|
get_handle
|
|
init
|
|
language_tag
|
|
maketext
|
|
new
|
|
whitelist
|
|
|
|
This list can be extended by either blacklisting additional "known bad"
|
|
methods, or whitelisting only "known good" methods.
|
|
|
|
To prevent specific methods from being called in bracket notation, use
|
|
the blacklist() method:
|
|
|
|
my $lh = MyProgram::L10N->get_handle();
|
|
$lh->blacklist(qw{my_internal_method my_other_method});
|
|
$lh->maketext('[my_internal_method]'); # dies
|
|
|
|
To limit the allowed bracked notation methods to a specific list, use the
|
|
whitelist() method:
|
|
|
|
my $lh = MyProgram::L10N->get_handle();
|
|
$lh->whitelist('numerate', 'numf');
|
|
$lh->maketext('[_1] [numerate, _1,shoe,shoes]', 12); # works
|
|
$lh->maketext('[my_internal_method]'); # dies
|
|
|
|
The blacklist() and whitelist() methods extend their internal lists
|
|
whenever they are called. To reset the blacklist or whitelist, create
|
|
a new maketext object.
|
|
|
|
my $lh = MyProgram::L10N->get_handle();
|
|
$lh->blacklist('numerate');
|
|
$lh->blacklist('numf');
|
|
$lh->maketext('[_1] [numerate,_1,shoe,shoes]', 12); # dies
|
|
|
|
For lexicons that use an internal cache, translations which have already
|
|
been cached in their compiled form are not affected by subsequent changes
|
|
to the whitelist or blacklist settings. Lexicons that use an external
|
|
cache will have their cache cleared whenever the whitelist of blacklist
|
|
setings change. The difference between the two types of caching is explained
|
|
in the "Readonly Lexicons" section.
|
|
|
|
Methods disallowed by the blacklist cannot be permitted by the
|
|
whitelist.
|
|
|
|
=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} = $compiled
|
|
|
|
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;
|
|
our $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 L<http://sunsite.dk/RFC/rfc/rfc3066.html>
|
|
|
|
RFC 2277, I<IETF Policy on Character Sets and Languages>
|
|
is at L<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<L<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. Observe 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
|