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3  Localization
4
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6    Standard Contents
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8  Localization
9  <a id="id-1.3.4.6.1.1.1" class="indexterm"></a>
10</h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="section"><a href="localization.html#std.localization.locales">Locales</a></span></dt><dd><dl><dt><span class="section"><a href="localization.html#std.localization.locales.locale">locale</a></span></dt><dd><dl><dt><span class="section"><a href="localization.html#locales.locale.req">Requirements</a></span></dt><dt><span class="section"><a href="localization.html#locales.locale.design">Design</a></span></dt><dt><span class="section"><a href="localization.html#locales.locale.impl">Implementation</a></span></dt><dd><dl><dt><span class="section"><a href="localization.html#locale.impl.c">Interacting with "C" locales</a></span></dt></dl></dd><dt><span class="section"><a href="localization.html#locales.locale.future">Future</a></span></dt></dl></dd></dl></dd><dt><span class="section"><a href="facets.html">Facets</a></span></dt><dd><dl><dt><span class="section"><a href="facets.html#std.localization.facet.ctype">ctype</a></span></dt><dd><dl><dt><span class="section"><a href="facets.html#facet.ctype.impl">Implementation</a></span></dt><dd><dl><dt><span class="section"><a href="facets.html#facet.ctype.impl.spec">Specializations</a></span></dt></dl></dd><dt><span class="section"><a href="facets.html#facet.ctype.future">Future</a></span></dt></dl></dd><dt><span class="section"><a href="facets.html#std.localization.facet.codecvt">codecvt</a></span></dt><dd><dl><dt><span class="section"><a href="facets.html#facet.codecvt.req">Requirements</a></span></dt><dt><span class="section"><a href="facets.html#facet.codecvt.design">Design</a></span></dt><dd><dl><dt><span class="section"><a href="facets.html#codecvt.design.wchar_t_size"><span class="type">wchar_t</span> Size</a></span></dt><dt><span class="section"><a href="facets.html#codecvt.design.unicode">Support for Unicode</a></span></dt><dt><span class="section"><a href="facets.html#codecvt.design.issues">Other Issues</a></span></dt></dl></dd><dt><span class="section"><a href="facets.html#facet.codecvt.impl">Implementation</a></span></dt><dt><span class="section"><a href="facets.html#facet.codecvt.use">Use</a></span></dt><dt><span class="section"><a href="facets.html#facet.codecvt.future">Future</a></span></dt></dl></dd><dt><span class="section"><a href="facets.html#std.localization.facet.messages">messages</a></span></dt><dd><dl><dt><span class="section"><a href="facets.html#facet.messages.req">Requirements</a></span></dt><dt><span class="section"><a href="facets.html#facet.messages.design">Design</a></span></dt><dt><span class="section"><a href="facets.html#facet.messages.impl">Implementation</a></span></dt><dd><dl><dt><span class="section"><a href="facets.html#messages.impl.models">Models</a></span></dt><dt><span class="section"><a href="facets.html#messages.impl.gnu">The GNU Model</a></span></dt></dl></dd><dt><span class="section"><a href="facets.html#facet.messages.use">Use</a></span></dt><dt><span class="section"><a href="facets.html#facet.messages.future">Future</a></span></dt></dl></dd></dl></dd></dl></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="std.localization.locales"></a>Locales</h2></div></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="std.localization.locales.locale"></a>locale</h3></div></div></div><p>
11Describes the basic locale object, including nested
12classes id, facet, and the reference-counted implementation object,
13class _Impl.
14</p><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="locales.locale.req"></a>Requirements</h4></div></div></div><p>
15Class locale is non-templatized and has two distinct types nested
16inside of it:
17</p><div class="blockquote"><blockquote class="blockquote"><p>
18<span class="emphasis"><em>
19class facet
2022.1.1.1.2 Class locale::facet
21</em></span>
22</p></blockquote></div><p>
23Facets actually implement locale functionality. For instance, a facet
24called numpunct is the data object that can be used to query for the
25thousands separator in the locale.
26</p><p>
27Literally, a facet is strictly defined:
28</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>
29      Containing the following public data member:
30    </p><p>
31      <code class="code">static locale::id id;</code>
32    </p></li><li class="listitem"><p>
33      Derived from another facet:
34    </p><p>
35      <code class="code">class gnu_codecvt: public std::ctype&lt;user-defined-type&gt;</code>
36    </p></li></ul></div><p>
37Of interest in this class are the memory management options explicitly
38specified as an argument to facet's constructor. Each constructor of a
39facet class takes a std::size_t __refs argument: if __refs == 0, the
40facet is deleted when the locale containing it is destroyed. If __refs
41== 1, the facet is not destroyed, even when it is no longer
42referenced.
43</p><div class="blockquote"><blockquote class="blockquote"><p>
44<span class="emphasis"><em>
45class id
4622.1.1.1.3 - Class locale::id
47</em></span>
48</p></blockquote></div><p>
49Provides an index for looking up specific facets.
50</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="locales.locale.design"></a>Design</h4></div></div></div><p>
51The major design challenge is fitting an object-orientated and
52non-global locale design on top of POSIX and other relevant standards,
53which include the Single Unix (nee X/Open.)
54</p><p>
55Because C and earlier versions of POSIX fall down so completely,
56portability is an issue.
57</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="locales.locale.impl"></a>Implementation</h4></div></div></div><div class="section"><div class="titlepage"><div><div><h5 class="title"><a id="locale.impl.c"></a>Interacting with "C" locales</h5></div></div></div><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>
58       <code class="code">locale -a</code> displays available locales.
59     </p><div class="blockquote"><blockquote class="blockquote"><pre class="programlisting">
60af_ZA
61ar_AE
62ar_AE.utf8
63ar_BH
64ar_BH.utf8
65ar_DZ
66ar_DZ.utf8
67ar_EG
68ar_EG.utf8
69ar_IN
70ar_IQ
71ar_IQ.utf8
72ar_JO
73ar_JO.utf8
74ar_KW
75ar_KW.utf8
76ar_LB
77ar_LB.utf8
78ar_LY
79ar_LY.utf8
80ar_MA
81ar_MA.utf8
82ar_OM
83ar_OM.utf8
84ar_QA
85ar_QA.utf8
86ar_SA
87ar_SA.utf8
88ar_SD
89ar_SD.utf8
90ar_SY
91ar_SY.utf8
92ar_TN
93ar_TN.utf8
94ar_YE
95ar_YE.utf8
96be_BY
97be_BY.utf8
98bg_BG
99bg_BG.utf8
100br_FR
101bs_BA
102C
103ca_ES
104ca_ES@euro
105ca_ES.utf8
106ca_ES.utf8@euro
107cs_CZ
108cs_CZ.utf8
109cy_GB
110da_DK
111da_DK.iso885915
112da_DK.utf8
113de_AT
114de_AT@euro
115de_AT.utf8
116de_AT.utf8@euro
117de_BE
118de_BE@euro
119de_BE.utf8
120de_BE.utf8@euro
121de_CH
122de_CH.utf8
123de_DE
124de_DE@euro
125de_DE.utf8
126de_DE.utf8@euro
127de_LU
128de_LU@euro
129de_LU.utf8
130de_LU.utf8@euro
131el_GR
132el_GR.utf8
133en_AU
134en_AU.utf8
135en_BW
136en_BW.utf8
137en_CA
138en_CA.utf8
139en_DK
140en_DK.utf8
141en_GB
142en_GB.iso885915
143en_GB.utf8
144en_HK
145en_HK.utf8
146en_IE
147en_IE@euro
148en_IE.utf8
149en_IE.utf8@euro
150en_IN
151en_NZ
152en_NZ.utf8
153en_PH
154en_PH.utf8
155en_SG
156en_SG.utf8
157en_US
158en_US.iso885915
159en_US.utf8
160en_ZA
161en_ZA.utf8
162en_ZW
163en_ZW.utf8
164es_AR
165es_AR.utf8
166es_BO
167es_BO.utf8
168es_CL
169es_CL.utf8
170es_CO
171es_CO.utf8
172es_CR
173es_CR.utf8
174es_DO
175es_DO.utf8
176es_EC
177es_EC.utf8
178es_ES
179es_ES@euro
180es_ES.utf8
181es_ES.utf8@euro
182es_GT
183es_GT.utf8
184es_HN
185es_HN.utf8
186es_MX
187es_MX.utf8
188es_NI
189es_NI.utf8
190es_PA
191es_PA.utf8
192es_PE
193es_PE.utf8
194es_PR
195es_PR.utf8
196es_PY
197es_PY.utf8
198es_SV
199es_SV.utf8
200es_US
201es_US.utf8
202es_UY
203es_UY.utf8
204es_VE
205es_VE.utf8
206et_EE
207et_EE.utf8
208eu_ES
209eu_ES@euro
210eu_ES.utf8
211eu_ES.utf8@euro
212fa_IR
213fi_FI
214fi_FI@euro
215fi_FI.utf8
216fi_FI.utf8@euro
217fo_FO
218fo_FO.utf8
219fr_BE
220fr_BE@euro
221fr_BE.utf8
222fr_BE.utf8@euro
223fr_CA
224fr_CA.utf8
225fr_CH
226fr_CH.utf8
227fr_FR
228fr_FR@euro
229fr_FR.utf8
230fr_FR.utf8@euro
231fr_LU
232fr_LU@euro
233fr_LU.utf8
234fr_LU.utf8@euro
235ga_IE
236ga_IE@euro
237ga_IE.utf8
238ga_IE.utf8@euro
239gl_ES
240gl_ES@euro
241gl_ES.utf8
242gl_ES.utf8@euro
243gv_GB
244gv_GB.utf8
245he_IL
246he_IL.utf8
247hi_IN
248hr_HR
249hr_HR.utf8
250hu_HU
251hu_HU.utf8
252id_ID
253id_ID.utf8
254is_IS
255is_IS.utf8
256it_CH
257it_CH.utf8
258it_IT
259it_IT@euro
260it_IT.utf8
261it_IT.utf8@euro
262iw_IL
263iw_IL.utf8
264ja_JP.eucjp
265ja_JP.utf8
266ka_GE
267kl_GL
268kl_GL.utf8
269ko_KR.euckr
270ko_KR.utf8
271kw_GB
272kw_GB.utf8
273lt_LT
274lt_LT.utf8
275lv_LV
276lv_LV.utf8
277mi_NZ
278mk_MK
279mk_MK.utf8
280mr_IN
281ms_MY
282ms_MY.utf8
283mt_MT
284mt_MT.utf8
285nl_BE
286nl_BE@euro
287nl_BE.utf8
288nl_BE.utf8@euro
289nl_NL
290nl_NL@euro
291nl_NL.utf8
292nl_NL.utf8@euro
293nn_NO
294nn_NO.utf8
295no_NO
296no_NO.utf8
297oc_FR
298pl_PL
299pl_PL.utf8
300POSIX
301pt_BR
302pt_BR.utf8
303pt_PT
304pt_PT@euro
305pt_PT.utf8
306pt_PT.utf8@euro
307ro_RO
308ro_RO.utf8
309ru_RU
310ru_RU.koi8r
311ru_RU.utf8
312ru_UA
313ru_UA.utf8
314se_NO
315sk_SK
316sk_SK.utf8
317sl_SI
318sl_SI.utf8
319sq_AL
320sq_AL.utf8
321sr_YU
322sr_YU@cyrillic
323sr_YU.utf8
324sr_YU.utf8@cyrillic
325sv_FI
326sv_FI@euro
327sv_FI.utf8
328sv_FI.utf8@euro
329sv_SE
330sv_SE.iso885915
331sv_SE.utf8
332ta_IN
333te_IN
334tg_TJ
335th_TH
336th_TH.utf8
337tl_PH
338tr_TR
339tr_TR.utf8
340uk_UA
341uk_UA.utf8
342ur_PK
343uz_UZ
344vi_VN
345vi_VN.tcvn
346wa_BE
347wa_BE@euro
348yi_US
349zh_CN
350zh_CN.gb18030
351zh_CN.gbk
352zh_CN.utf8
353zh_HK
354zh_HK.utf8
355zh_TW
356zh_TW.euctw
357zh_TW.utf8
358</pre></blockquote></div></li><li class="listitem"><p>
359       <code class="code">`locale`</code> displays environmental variables that
360       impact how locale("") will be deduced.
361     </p><div class="blockquote"><blockquote class="blockquote"><pre class="programlisting">
362LANG=en_US
363LC_CTYPE="en_US"
364LC_NUMERIC="en_US"
365LC_TIME="en_US"
366LC_COLLATE="en_US"
367LC_MONETARY="en_US"
368LC_MESSAGES="en_US"
369LC_PAPER="en_US"
370LC_NAME="en_US"
371LC_ADDRESS="en_US"
372LC_TELEPHONE="en_US"
373LC_MEASUREMENT="en_US"
374LC_IDENTIFICATION="en_US"
375LC_ALL=
376</pre></blockquote></div></li></ul></div><p>
377From Josuttis, p. 697-698, which says, that "there is only *one*
378relation (of the C++ locale mechanism) to the C locale mechanism: the
379global C locale is modified if a named C++ locale object is set as the
380global locale" (emphasis Paolo), that is:
381</p><pre class="programlisting">std::locale::global(std::locale(""));</pre><p>affects the C functions as if the following call was made:</p><pre class="programlisting">std::setlocale(LC_ALL, "");</pre><p>
382  On the other hand, there is *no* vice versa, that is, calling
383  setlocale has *no* whatsoever on the C++ locale mechanism, in
384  particular on the working of locale(""), which constructs the locale
385  object from the environment of the running program, that is, in
386  practice, the set of LC_ALL, LANG, etc. variable of the shell.
387</p></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="locales.locale.future"></a>Future</h4></div></div></div><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>
388       Locale initialization: at what point does _S_classic, _S_global
389       get initialized? Can named locales assume this initialization
390       has already taken place?
391     </p></li><li class="listitem"><p>
392       Document how named locales error check when filling data
393       members. I.e., a fr_FR locale that doesn't have
394       numpunct::truename(): does it use "true"? Or is it a blank
395       string? What's the convention?
396   </p></li><li class="listitem"><p>
397       Explain how locale aliasing happens. When does "de_DE" use "de"
398       information? What is the rule for locales composed of just an
399       ISO language code (say, "de") and locales with both an ISO
400       language code and ISO country code (say, "de_DE").
401     </p></li><li class="listitem"><p>
402       What should non-required facet instantiations do?  If the
403       generic implementation is provided, then how to end-users
404       provide specializations?
405   </p></li></ul></div></div><div class="bibliography"><div class="titlepage"><div><div><h4 class="title"><a id="locales.locale.biblio"></a>Bibliography</h4></div></div></div><div class="biblioentry"><a id="id-1.3.4.6.2.2.7.2"></a><p><span class="citetitle"><em class="citetitle">
406      The GNU C Library
407    </em>. </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">
408      Chapters 6 Character Set Handling and 7 Locales and
409      Internationalization
410    . </span></p></div><div class="biblioentry"><a id="id-1.3.4.6.2.2.7.3"></a><p><span class="citetitle"><em class="citetitle">
411      Correspondence
412    </em>. </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="id-1.3.4.6.2.2.7.4"></a><p><span class="citetitle"><em class="citetitle">
413      ISO/IEC 14882:1998 Programming languages - C++
414    </em>. </span><span class="copyright">Copyright © 1998 ISO. </span></p></div><div class="biblioentry"><a id="id-1.3.4.6.2.2.7.5"></a><p><span class="citetitle"><em class="citetitle">
415      ISO/IEC 9899:1999 Programming languages - C
416    </em>. </span><span class="copyright">Copyright © 1999 ISO. </span></p></div><div class="biblioentry"><a id="id-1.3.4.6.2.2.7.6"></a><p><span class="title"><em>
417	<a class="link" href="https://pubs.opengroup.org/onlinepubs/9699919799/" target="_top">
418      System Interface Definitions, Issue 7 (IEEE Std. 1003.1-2008)
419	</a>
420      </em>. </span><span class="copyright">Copyright © 2008
421	The Open Group/The Institute of Electrical and Electronics
422	Engineers, Inc.
423      . </span></p></div><div class="biblioentry"><a id="id-1.3.4.6.2.2.7.7"></a><p><span class="citetitle"><em class="citetitle">
424      The C++ Programming Language, Special Edition
425    </em>. </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">
426	Addison Wesley
427      . </span></span></p></div><div class="biblioentry"><a id="id-1.3.4.6.2.2.7.8"></a><p><span class="citetitle"><em class="citetitle">
428      Standard C++ IOStreams and Locales
429    </em>. </span><span class="subtitle">
430      Advanced Programmer's Guide and Reference
431    . </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">
432	Addison Wesley Longman
433      . </span></span></p></div></div></div></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="strings.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="std_contents.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="facets.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chapter 7. 
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