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2001-09-17 Phil Edwards <pme@gcc.gnu.org> * docs/html/configopts.html: HTML to XHTML change. Lowercase tags. * docs/html/documentation.html: Likewise. * docs/html/explanations.html: Likewise. * docs/html/install.html: Likewise. * docs/html/17_intro/howto.html: Likewise. * docs/html/18_support/howto.html: Likewise. * docs/html/19_diagnostics/howto.html: Likewise. * docs/html/20_util/howto.html: Likewise. * docs/html/21_strings/howto.html: Likewise. * docs/html/22_locale/codecvt.html: Likewise. * docs/html/22_locale/ctype.html: Likewise. * docs/html/22_locale/howto.html: Likewise. * docs/html/22_locale/locale.html: Likewise. * docs/html/22_locale/messages.html: Likewise. * docs/html/23_containers/howto.html: Likewise. * docs/html/24_iterators/howto.html: Likewise. * docs/html/25_algorithms/howto.html: Likewise. * docs/html/26_numerics/howto.html: Likewise. * docs/html/27_io/howto.html: Likewise. * docs/html/ext/howto.html: Likewise. * docs/html/faq/index.html: Likewise. * docs/html/faq/index.txt: Regenerated. From-SVN: r45668
144 lines
3.3 KiB
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144 lines
3.3 KiB
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<h1>
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Notes on the locale implementation.
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</h1>
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</head>
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<I>
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prepared by Benjamin Kosnik (bkoz@redhat.com) on August 8, 2001
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</I>
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<p>
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<h2>
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1. Abstract Describes the basic locale object, including nested
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classes id, facet, and the reference-counted implementation object,
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class _Impl.
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</h2>
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<p>
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</p>
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<p>
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<h2>
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2. What the standard says
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See Chapter 22 of the standard.
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</h2>
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<p>
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<h2>
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3. Problems with "C" locales : global locales, termination.
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</h2>
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<p>
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The major problem is fitting an object-orientated and non-global locale
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design ontop of POSIX and other relevant stanards, which include the
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Single Unix (nee X/Open.)
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Because POSIX falls down so completely, portibility is an issue.
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<p>
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<h2>
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4. Design
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</h2>
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Class locale in non-templatized and has three distinct types nested
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inside of it:
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class facet
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22.1.1.1.2 Class locale::facet
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Facets actually implement locale functionality. For instance, a facet
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called numpunct is the data objects that can be used to query for the
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thousands seperator is in the German locale.
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Literally, a facet is strictly defined:
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- containing
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public:
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static locale::id id;
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- or derived from another facet
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The only other thing of interest in this class is the memory
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management of facets. Each constructor of a facet class takes a
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std::size_t __refs argument: if __refs == 0, the facet is deleted when
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no longer used. if __refs == 1, the facet is not destroyed, even when
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it is no longer reference.
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class id
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Provides an index for looking up specific facets.
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class _Impl
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<p>
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<h2>
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5. Examples
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</h2>
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<pre>
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typedef __locale_t locale;
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</pre>
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More information can be found in the following testcases:
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<ul>
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<li> testsuite/22_locale/ctype_char_members.cc
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<li> testsuite/22_locale/ctype_wchar_t_members.cc
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</ul>
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<p>
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<h2>
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6. Unresolved Issues
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</h2>
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<ul>
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<li> locale -a displays available locales on linux
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<li> locale initialization: at what point does _S_classic,
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_S_global get initialized? Can named locales assume this
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initialization has already taken place?
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<li> document how named locales error check when filling data
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members. Ie, a fr_FR locale that doesn't have
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numpunct::truename(): does it use "true"? Or is it a blank
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string? What's the convention?
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<li> explain how locale aliasing happens. When does "de_DE"
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use "de" information? What is the rule for locales composed of
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just an ISO language code (say, "de") and locales with both an
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ISO language code and ISO country code (say, "de_DE").
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</ul>
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<p>
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<h2>
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7. Acknowledgments
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</h2>
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<p>
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<h2>
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8. Bibliography / Referenced Documents
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</h2>
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Drepper, Ulrich, GNU libc (glibc) 2.2 manual. In particular, Chapters "6. Character Set Handling" and "7 Locales and Internationalization"
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<p>
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Drepper, Ulrich, Numerous, late-night email correspondence
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<p>
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ISO/IEC 14882:1998 Programming languages - C++
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<p>
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ISO/IEC 9899:1999 Programming languages - C
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<p>
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Langer, Angelika and Klaus Kreft, Standard C++ IOStreams and Locales, Advanced Programmer's Guide and Reference, Addison Wesley Longman, Inc. 2000
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<p>
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Stroustrup, Bjarne, Appendix D, The C++ Programming Language, Special Edition, Addison Wesley, Inc. 2000
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<p>
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System Interface Definitions, Issue 6 (IEEE Std. 1003.1-200x)
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The Open Group/The Institute of Electrical and Electronics Engineers, Inc.
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http://www.opennc.org/austin/docreg.html
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