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diff --git a/libstdc++-v3/docs/html/22_locale/messages.html b/libstdc++-v3/docs/html/22_locale/messages.html deleted file mode 100644 index 41e94a42f83..00000000000 --- a/libstdc++-v3/docs/html/22_locale/messages.html +++ /dev/null @@ -1,461 +0,0 @@ -<?xml version="1.0" encoding="ISO-8859-1"?> -<!DOCTYPE html - PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" - "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> - -<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> -<head> - <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" /> - <meta name="AUTHOR" content="bkoz@redhat.com (Benjamin Kosnik)" /> - <meta name="KEYWORDS" content="HOWTO, libstdc++, GCC, g++, libg++, STL" /> - <meta name="DESCRIPTION" content="Notes on the messages implementation." /> - <title>Notes on the messages implementation.</title> -<link rel="StyleSheet" href="../lib3styles.css" type="text/css" /> -<link rel="Start" href="../documentation.html" type="text/html" - title="GNU C++ Standard Library" /> -<link rel="Bookmark" href="howto.html" type="text/html" title="Localization" /> -<link rel="Copyright" href="../17_intro/license.html" type="text/html" /> -<link rel="Help" href="../faq/index.html" type="text/html" title="F.A.Q." /> -</head> -<body> -<h1> -Notes on the messages implementation. -</h1> -<em> -prepared by Benjamin Kosnik (bkoz@redhat.com) on August 8, 2001 -</em> - -<h2> -1. Abstract -</h2> -<p> -The std::messages facet implements message retrieval functionality -equivalent to Java's java.text.MessageFormat .using either GNU gettext -or IEEE 1003.1-200 functions. -</p> - -<h2> -2. What the standard says -</h2> -The std::messages facet is probably the most vaguely defined facet in -the standard library. It's assumed that this facility was built into -the standard library in order to convert string literals from one -locale to the other. For instance, converting the "C" locale's -<code>const char* c = "please"</code> to a German-localized <code>"bitte"</code> -during program execution. - -<blockquote> -22.2.7.1 - Template class messages [lib.locale.messages] -</blockquote> - -This class has three public member functions, which directly -correspond to three protected virtual member functions. - -The public member functions are: - -<p> -<code>catalog open(const string&, const locale&) const</code> -</p> - -<p> -<code>string_type get(catalog, int, int, const string_type&) const</code> -</p> - -<p> -<code>void close(catalog) const</code> -</p> - -<p> -While the virtual functions are: -</p> - -<p> -<code>catalog do_open(const string&, const locale&) const</code> -</p> -<blockquote> -<em> --1- Returns: A value that may be passed to get() to retrieve a -message, from the message catalog identified by the string name -according to an implementation-defined mapping. The result can be used -until it is passed to close(). Returns a value less than 0 if no such -catalog can be opened. -</em> -</blockquote> - -<p> -<code>string_type do_get(catalog, int, int, const string_type&) const</code> -</p> -<blockquote> -<em> --3- Requires: A catalog cat obtained from open() and not yet closed. --4- Returns: A message identified by arguments set, msgid, and dfault, -according to an implementation-defined mapping. If no such message can -be found, returns dfault. -</em> -</blockquote> - -<p> -<code>void do_close(catalog) const</code> -</p> -<blockquote> -<em> --5- Requires: A catalog cat obtained from open() and not yet closed. --6- Effects: Releases unspecified resources associated with cat. --7- Notes: The limit on such resources, if any, is implementation-defined. -</em> -</blockquote> - - -<h2> -3. Problems with "C" messages: thread safety, -over-specification, and assumptions. -</h2> -A couple of notes on the standard. - -<p> -First, why is <code>messages_base::catalog</code> specified as a typedef -to int? This makes sense for implementations that use -<code>catopen</code>, but not for others. Fortunately, it's not heavily -used and so only a minor irritant. -</p> - -<p> -Second, by making the member functions <code>const</code>, it is -impossible to save state in them. Thus, storing away information used -in the 'open' member function for use in 'get' is impossible. This is -unfortunate. -</p> - -<p> -The 'open' member function in particular seems to be oddly -designed. The signature seems quite peculiar. Why specify a <code>const -string& </code> argument, for instance, instead of just <code>const -char*</code>? Or, why specify a <code>const locale&</code> argument that is -to be used in the 'get' member function? How, exactly, is this locale -argument useful? What was the intent? It might make sense if a locale -argument was associated with a given default message string in the -'open' member function, for instance. Quite murky and unclear, on -reflection. -</p> - -<p> -Lastly, it seems odd that messages, which explicitly require code -conversion, don't use the codecvt facet. Because the messages facet -has only one template parameter, it is assumed that ctype, and not -codecvt, is to be used to convert between character sets. -</p> - -<p> -It is implicitly assumed that the locale for the default message -string in 'get' is in the "C" locale. Thus, all source code is assumed -to be written in English, so translations are always from "en_US" to -other, explicitly named locales. -</p> - -<h2> -4. Design and Implementation Details -</h2> -This is a relatively simple class, on the face of it. The standard -specifies very little in concrete terms, so generic implementations -that are conforming yet do very little are the norm. Adding -functionality that would be useful to programmers and comparable to -Java's java.text.MessageFormat takes a bit of work, and is highly -dependent on the capabilities of the underlying operating system. - -<p> -Three different mechanisms have been provided, selectable via -configure flags: -</p> - -<ul> - <li> generic - <p> - This model does very little, and is what is used by default. - </p> - </li> - - <li> gnu - <p> - The gnu model is complete and fully tested. It's based on the - GNU gettext package, which is part of glibc. It uses the functions - <code>textdomain, bindtextdomain, gettext</code> - to implement full functionality. Creating message - catalogs is a relatively straight-forward process and is - lightly documented below, and fully documented in gettext's - distributed documentation. - </p> - </li> - - <li> ieee_1003.1-200x - <p> - This is a complete, though untested, implementation based on - the IEEE standard. The functions - <code>catopen, catgets, catclose</code> - are used to retrieve locale-specific messages given the - appropriate message catalogs that have been constructed for - their use. Note, the script <code> po2msg.sed</code> that is part - of the gettext distribution can convert gettext catalogs into - catalogs that <code>catopen</code> can use. - </p> - </li> -</ul> - -<p> -A new, standards-conformant non-virtual member function signature was -added for 'open' so that a directory could be specified with a given -message catalog. This simplifies calling conventions for the gnu -model. -</p> - -<p> -The rest of this document discusses details of the GNU model. -</p> - -<p> -The messages facet, because it is retrieving and converting between -characters sets, depends on the ctype and perhaps the codecvt facet in -a given locale. In addition, underlying "C" library locale support is -necessary for more than just the <code>LC_MESSAGES</code> mask: -<code>LC_CTYPE</code> is also necessary. To avoid any unpleasantness, all -bits of the "C" mask (ie <code>LC_ALL</code>) are set before retrieving -messages. -</p> - -<p> -Making the message catalogs can be initially tricky, but become quite -simple with practice. For complete info, see the gettext -documentation. Here's an idea of what is required: -</p> - -<ul> - <li> Make a source file with the required string literals - that need to be translated. See - <code>intl/string_literals.cc</code> for an example. - </li> - - <li> Make initial catalog (see "4 Making the PO Template File" - from the gettext docs). - <p> - <code> xgettext --c++ --debug string_literals.cc -o libstdc++.pot </code> - </p> - </li> - - <li> Make language and country-specific locale catalogs. - <p> - <code>cp libstdc++.pot fr_FR.po</code> - </p> - <p> - <code>cp libstdc++.pot de_DE.po</code> - </p> - </li> - - <li> Edit localized catalogs in emacs so that strings are - translated. - <p> - <code>emacs fr_FR.po</code> - </p> - </li> - - <li> Make the binary mo files. - <p> - <code>msgfmt fr_FR.po -o fr_FR.mo</code> - </p> - <p> - <code>msgfmt de_DE.po -o de_DE.mo</code> - </p> - </li> - - <li> Copy the binary files into the correct directory structure. - <p> - <code>cp fr_FR.mo (dir)/fr_FR/LC_MESSAGES/libstdc++-v3.mo</code> - </p> - <p> - <code>cp de_DE.mo (dir)/de_DE/LC_MESSAGES/libstdc++-v3.mo</code> - </p> - </li> - - <li> Use the new message catalogs. - <p> - <code>locale loc_de("de_DE");</code> - </p> - <p> - <code> - use_facet<messages<char> >(loc_de).open("libstdc++", locale(), dir); - </code> - </p> - </li> -</ul> - -<h2> -5. Examples -</h2> - -<ul> - <li> message converting, simple example using the GNU model. - -<pre> -#include <iostream> -#include <locale> -using namespace std; - -void test01() -{ - typedef messages<char>::catalog catalog; - const char* dir = - "/mnt/egcs/build/i686-pc-linux-gnu/libstdc++-v3/po/share/locale"; - const locale loc_de("de_DE"); - const messages<char>& mssg_de = use_facet<messages<char> >(loc_de); - - catalog cat_de = mssg_de.open("libstdc++", loc_de, dir); - string s01 = mssg_de.get(cat_de, 0, 0, "please"); - string s02 = mssg_de.get(cat_de, 0, 0, "thank you"); - cout << "please in german:" << s01 << '\n'; - cout << "thank you in german:" << s02 << '\n'; - mssg_de.close(cat_de); -} -</pre> - </li> -</ul> - -More information can be found in the following testcases: -<ul> -<li> testsuite/22_locale/messages.cc </li> -<li> testsuite/22_locale/messages_byname.cc </li> -<li> testsuite/22_locale/messages_char_members.cc </li> -</ul> - -<h2> -6. Unresolved Issues -</h2> -<ul> -<li> Things that are sketchy, or remain unimplemented: - <ul> - <li>_M_convert_from_char, _M_convert_to_char are in - flux, depending on how the library ends up doing - character set conversions. It might not be possible to - do a real character set based conversion, due to the - fact that the template parameter for messages is not - enough to instantiate the codecvt facet (1 supplied, - need at least 2 but would prefer 3). - </li> - - <li> There are issues with gettext needing the global - locale set to extract a message. This dependence on - the global locale makes the current "gnu" model non - MT-safe. Future versions of glibc, ie glibc 2.3.x will - fix this, and the C++ library bits are already in - place. - </li> - </ul> -</li> - -<li> Development versions of the GNU "C" library, glibc 2.3 will allow - a more efficient, MT implementation of std::messages, and will - allow the removal of the _M_name_messages data member. If this - is done, it will change the library ABI. The C++ parts to - support glibc 2.3 have already been coded, but are not in use: - once this version of the "C" library is released, the marked - parts of the messages implementation can be switched over to - the new "C" library functionality. -</li> -<li> At some point in the near future, std::numpunct will probably use - std::messages facilities to implement truename/falename - correctly. This is currently not done, but entries in - libstdc++.pot have already been made for "true" and "false" - string literals, so all that remains is the std::numpunct - coding and the configure/make hassles to make the installed - library search its own catalog. Currently the libstdc++.mo - catalog is only searched for the testsuite cases involving - messages members. -</li> - -<li> The following member functions: - - <p> - <code> - catalog - open(const basic_string<char>& __s, const locale& __loc) const - </code> - </p> - - <p> - <code> - catalog - open(const basic_string<char>&, const locale&, const char*) const; - </code> - </p> - - <p> - Don't actually return a "value less than 0 if no such catalog - can be opened" as required by the standard in the "gnu" - model. As of this writing, it is unknown how to query to see - if a specified message catalog exists using the gettext - package. - </p> -</li> -</ul> - -<h2> -7. Acknowledgments -</h2> -Ulrich Drepper for the character set explanations, gettext details, -and patient answering of late-night questions, Tom Tromey for the java details. - - -<h2> -8. Bibliography / Referenced Documents -</h2> - -Drepper, Ulrich, GNU libc (glibc) 2.2 manual. In particular, Chapters -"7 Locales and Internationalization" - -<p> -Drepper, Ulrich, Thread-Aware Locale Model, A proposal. This is a -draft document describing the design of glibc 2.3 MT locale -functionality. -</p> - -<p> -Drepper, Ulrich, Numerous, late-night email correspondence -</p> - -<p> -ISO/IEC 9899:1999 Programming languages - C -</p> - -<p> -ISO/IEC 14882:1998 Programming languages - C++ -</p> - -<p> -Java 2 Platform, Standard Edition, v 1.3.1 API Specification. In -particular, java.util.Properties, java.text.MessageFormat, -java.util.Locale, java.util.ResourceBundle. -http://java.sun.com/j2se/1.3/docs/api -</p> - -<p> -System Interface Definitions, Issue 7 (IEEE Std. 1003.1-200x) -The Open Group/The Institute of Electrical and Electronics Engineers, Inc. -In particular see lines 5268-5427. -http://www.opennc.org/austin/docreg.html -</p> - -<p> GNU gettext tools, version 0.10.38, Native Language Support -Library and Tools. -http://sources.redhat.com/gettext -</p> - -<p> -Langer, Angelika and Klaus Kreft, Standard C++ IOStreams and Locales, -Advanced Programmer's Guide and Reference, Addison Wesley Longman, -Inc. 2000. See page 725, Internationalized Messages. -</p> - -<p> -Stroustrup, Bjarne, Appendix D, The C++ Programming Language, Special Edition, Addison Wesley, Inc. 2000 -</p> - -</body> -</html> - |