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diff --git a/gcc-4.4.3/libstdc++-v3/doc/html/manual/messages.html b/gcc-4.4.3/libstdc++-v3/doc/html/manual/messages.html new file mode 100644 index 000000000..67327cc27 --- /dev/null +++ b/gcc-4.4.3/libstdc++-v3/doc/html/manual/messages.html @@ -0,0 +1,284 @@ +<?xml version="1.0" encoding="UTF-8" standalone="no"?> +<!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"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>messages</title><meta name="generator" content="DocBook XSL Stylesheets V1.74.0" /><meta name="keywords" content=" ISO C++ , messages " /><meta name="keywords" content=" ISO C++ , library " /><link rel="home" href="../spine.html" title="The GNU C++ Library Documentation" /><link rel="up" href="facets.html" title="Chapter 15. Facets aka Categories" /><link rel="prev" href="codecvt.html" title="codecvt" /><link rel="next" href="containers.html" title="Part VII. Containers" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">messages</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="codecvt.html">Prev</a> </td><th width="60%" align="center">Chapter 15. Facets aka Categories</th><td width="20%" align="right"> <a accesskey="n" href="containers.html">Next</a></td></tr></table><hr /></div><div class="sect1" lang="en" xml:lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="manual.localization.facet.messages"></a>messages</h2></div></div></div><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><div class="sect2" lang="en" xml:lang="en"><div class="titlepage"><div><div><h3 class="title"><a id="facet.messages.req"></a>Requirements</h3></div></div></div><p> +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 class="code">const char* c = "please"</code> to a German-localized <code class="code">"bitte"</code> +during program execution. +</p><div class="blockquote"><blockquote class="blockquote"><p> +22.2.7.1 - Template class messages [lib.locale.messages] +</p></blockquote></div><p> +This class has three public member functions, which directly +correspond to three protected virtual member functions. +</p><p> +The public member functions are: +</p><p> +<code class="code">catalog open(const string&, const locale&) const</code> +</p><p> +<code class="code">string_type get(catalog, int, int, const string_type&) const</code> +</p><p> +<code class="code">void close(catalog) const</code> +</p><p> +While the virtual functions are: +</p><p> +<code class="code">catalog do_open(const string&, const locale&) const</code> +</p><div class="blockquote"><blockquote class="blockquote"><p> +<span class="emphasis"><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></span> +</p></blockquote></div><p> +<code class="code">string_type do_get(catalog, int, int, const string_type&) const</code> +</p><div class="blockquote"><blockquote class="blockquote"><p> +<span class="emphasis"><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></span> +</p></blockquote></div><p> +<code class="code">void do_close(catalog) const</code> +</p><div class="blockquote"><blockquote class="blockquote"><p> +<span class="emphasis"><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></span> +</p></blockquote></div></div><div class="sect2" lang="en" xml:lang="en"><div class="titlepage"><div><div><h3 class="title"><a id="facet.messages.design"></a>Design</h3></div></div></div><p> +A couple of notes on the standard. +</p><p> +First, why is <code class="code">messages_base::catalog</code> specified as a typedef +to int? This makes sense for implementations that use +<code class="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 class="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 class="code">const +string& </code> argument, for instance, instead of just <code class="code">const +char*</code>? Or, why specify a <code class="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></div><div class="sect2" lang="en" xml:lang="en"><div class="titlepage"><div><div><h3 class="title"><a id="facet.messages.impl"></a>Implementation</h3></div></div></div><div class="sect3" lang="en" xml:lang="en"><div class="titlepage"><div><div><h4 class="title"><a id="messages.impl.models"></a>Models</h4></div></div></div><p> + 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><p> + Three different mechanisms have been provided, selectable via + configure flags: + </p><div class="itemizedlist"><ul type="disc"><li><p> + generic + </p><p> + This model does very little, and is what is used by default. + </p></li><li><p> + gnu + </p><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 class="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><p> + ieee_1003.1-200x + </p><p> + This is a complete, though untested, implementation based on + the IEEE standard. The functions <code class="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 class="code"> + po2msg.sed</code> that is part of the gettext distribution can + convert gettext catalogs into catalogs that + <code class="code">catopen</code> can use. + </p></li></ul></div><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></div><div class="sect3" lang="en" xml:lang="en"><div class="titlepage"><div><div><h4 class="title"><a id="messages.impl.gnu"></a>The GNU Model</h4></div></div></div><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 class="code">LC_MESSAGES</code> mask: <code class="code">LC_CTYPE</code> is also + necessary. To avoid any unpleasantness, all bits of the "C" mask + (i.e. <code class="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><div class="itemizedlist"><ul type="disc"><li><p> + Make a source file with the required string literals that need + to be translated. See <code class="code">intl/string_literals.cc</code> for + an example. + </p></li><li><p> + Make initial catalog (see "4 Making the PO Template File" from + the gettext docs).</p><p> + <code class="code"> xgettext --c++ --debug string_literals.cc -o libstdc++.pot </code> + </p></li><li><p>Make language and country-specific locale catalogs.</p><p> + <code class="code">cp libstdc++.pot fr_FR.po</code> + </p><p> + <code class="code">cp libstdc++.pot de_DE.po</code> + </p></li><li><p> + Edit localized catalogs in emacs so that strings are + translated. + </p><p> + <code class="code">emacs fr_FR.po</code> + </p></li><li><p>Make the binary mo files.</p><p> + <code class="code">msgfmt fr_FR.po -o fr_FR.mo</code> + </p><p> + <code class="code">msgfmt de_DE.po -o de_DE.mo</code> + </p></li><li><p>Copy the binary files into the correct directory structure.</p><p> + <code class="code">cp fr_FR.mo (dir)/fr_FR/LC_MESSAGES/libstdc++.mo</code> + </p><p> + <code class="code">cp de_DE.mo (dir)/de_DE/LC_MESSAGES/libstdc++.mo</code> + </p></li><li><p>Use the new message catalogs.</p><p> + <code class="code">locale loc_de("de_DE");</code> + </p><p> + <code class="code"> + use_facet<messages<char> >(loc_de).open("libstdc++", locale(), dir); + </code> + </p></li></ul></div></div></div><div class="sect2" lang="en" xml:lang="en"><div class="titlepage"><div><div><h3 class="title"><a id="facet.messages.use"></a>Use</h3></div></div></div><p> + A simple example using the GNU model of message conversion. + </p><pre class="programlisting"> +#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++/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></div><div class="sect2" lang="en" xml:lang="en"><div class="titlepage"><div><div><h3 class="title"><a id="facet.messages.future"></a>Future</h3></div></div></div><div class="itemizedlist"><ul type="disc"><li><p> + Things that are sketchy, or remain unimplemented: + </p><div class="itemizedlist"><ul type="circle"><li><p> + _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). + </p></li><li><p> + 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, i.e. glibc 2.3.x will fix this, and the C++ library + bits are already in place. + </p></li></ul></div></li><li><p> + 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. + </p></li><li><p> + At some point in the near future, std::numpunct will probably use + std::messages facilities to implement truename/falsename + 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. + </p></li><li><p> The following member functions:</p><p> + <code class="code"> + catalog + open(const basic_string<char>& __s, const locale& __loc) const + </code> + </p><p> + <code class="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></div></div><div class="bibliography"><div class="titlepage"><div><div><h3 class="title"><a id="facet.messages.biblio"></a>Bibliography</h3></div></div></div><div class="biblioentry"><a id="id427517"></a><p><span class="title"><i> + The GNU C Library + </i>. </span><span class="author"><span class="firstname">Roland</span> <span class="surname">McGrath</span>. </span><span class="author"><span class="firstname">Ulrich</span> <span class="surname">Drepper</span>. </span><span class="copyright">Copyright © 2007 FSF. </span><span class="pagenums">Chapters 6 Character Set Handling, and 7 Locales and Internationalization + . </span></p></div><div class="biblioentry"><a id="id391329"></a><p><span class="title"><i> + Correspondence + </i>. </span><span class="author"><span class="firstname">Ulrich</span> <span class="surname">Drepper</span>. </span><span class="copyright">Copyright © 2002 . </span></p></div><div class="biblioentry"><a id="id391358"></a><p><span class="title"><i> + ISO/IEC 14882:1998 Programming languages - C++ + </i>. </span><span class="copyright">Copyright © 1998 ISO. </span></p></div><div class="biblioentry"><a id="id514997"></a><p><span class="title"><i> + ISO/IEC 9899:1999 Programming languages - C + </i>. </span><span class="copyright">Copyright © 1999 ISO. </span></p></div><div class="biblioentry"><a id="id515015"></a><p><span class="title"><i> + System Interface Definitions, Issue 6 (IEEE Std. 1003.1-200x) + </i>. </span><span class="copyright">Copyright © 1999 + The Open Group/The Institute of Electrical and Electronics Engineers, Inc.. </span><span class="biblioid"> + <a class="ulink" href="http://www.opennc.org/austin/docreg.html" target="_top"> + </a> + . </span></p></div><div class="biblioentry"><a id="id427733"></a><p><span class="title"><i> + The C++ Programming Language, Special Edition + </i>. </span><span class="author"><span class="firstname">Bjarne</span> <span class="surname">Stroustrup</span>. </span><span class="copyright">Copyright © 2000 Addison Wesley, Inc.. </span><span class="pagenums">Appendix D. </span><span class="publisher"><span class="publishername"> + Addison Wesley + . </span></span></p></div><div class="biblioentry"><a id="id427774"></a><p><span class="title"><i> + Standard C++ IOStreams and Locales + </i>. </span><span class="subtitle"> + Advanced Programmer's Guide and Reference + . </span><span class="author"><span class="firstname">Angelika</span> <span class="surname">Langer</span>. </span><span class="author"><span class="firstname">Klaus</span> <span class="surname">Kreft</span>. </span><span class="copyright">Copyright © 2000 Addison Wesley Longman, Inc.. </span><span class="publisher"><span class="publishername"> + Addison Wesley Longman + . </span></span></p></div><div class="biblioentry"><a id="id402618"></a><p><span class="title"><i> + Java 2 Platform, Standard Edition, v 1.3.1 API Specification + </i>. </span><span class="pagenums">java.util.Properties, java.text.MessageFormat, +java.util.Locale, java.util.ResourceBundle. </span><span class="biblioid"> + <a class="ulink" href="http://java.sun.com/j2se/1.3/docs/api" target="_top"> + </a> + . </span></p></div><div class="biblioentry"><a id="id404627"></a><p><span class="title"><i> + GNU gettext tools, version 0.10.38, Native Language Support +Library and Tools. + </i>. </span><span class="biblioid"> + <a class="ulink" href="http://sources.redhat.com/gettext" target="_top"> + </a> + . </span></p></div></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="codecvt.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="facets.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="containers.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">codecvt </td><td width="20%" align="center"><a accesskey="h" href="../spine.html">Home</a></td><td width="40%" align="right" valign="top"> Part VII. + Containers + +</td></tr></table></div></body></html> |