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   3   Localization
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   8   Localization
   9   <a id="idm269891625280" 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#idm269891548288">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#manual.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>
  11 Describes the basic locale object, including nested
  12 classes id, facet, and the reference-counted implementation object,
  13 class _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>
  15 Class locale is non-templatized and has two distinct types nested
  16 inside of it:
  17 </p><div class="blockquote"><blockquote class="blockquote"><p>
  18 <span class="emphasis"><em>
  19 class facet
  20 22.1.1.1.2 Class locale::facet
  21 </em></span>
  22 </p></blockquote></div><p>
  23 Facets actually implement locale functionality. For instance, a facet
  24 called numpunct is the data object that can be used to query for the
  25 thousands separator in the locale.
  26 </p><p>
  27 Literally, 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>
  37 Of interest in this class are the memory management options explicitly
  38 specified as an argument to facet's constructor. Each constructor of a
  39 facet class takes a std::size_t __refs argument: if __refs == 0, the
  40 facet is deleted when the locale containing it is destroyed. If __refs
  41 == 1, the facet is not destroyed, even when it is no longer
  42 referenced.
  43 </p><div class="blockquote"><blockquote class="blockquote"><p>
  44 <span class="emphasis"><em>
  45 class id
  46 22.1.1.1.3 - Class locale::id
  47 </em></span>
  48 </p></blockquote></div><p>
  49 Provides 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>
  51 The major design challenge is fitting an object-orientated and
  52 non-global locale design on top of POSIX and other relevant standards,
  53 which include the Single Unix (nee X/Open.)
  54 </p><p>
  55 Because C and earlier versions of POSIX fall down so completely,
  56 portability 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">
  60 af_ZA
  61 ar_AE
  62 ar_AE.utf8
  63 ar_BH
  64 ar_BH.utf8
  65 ar_DZ
  66 ar_DZ.utf8
  67 ar_EG
  68 ar_EG.utf8
  69 ar_IN
  70 ar_IQ
  71 ar_IQ.utf8
  72 ar_JO
  73 ar_JO.utf8
  74 ar_KW
  75 ar_KW.utf8
  76 ar_LB
  77 ar_LB.utf8
  78 ar_LY
  79 ar_LY.utf8
  80 ar_MA
  81 ar_MA.utf8
  82 ar_OM
  83 ar_OM.utf8
  84 ar_QA
  85 ar_QA.utf8
  86 ar_SA
  87 ar_SA.utf8
  88 ar_SD
  89 ar_SD.utf8
  90 ar_SY
  91 ar_SY.utf8
  92 ar_TN
  93 ar_TN.utf8
  94 ar_YE
  95 ar_YE.utf8
  96 be_BY
  97 be_BY.utf8
  98 bg_BG
  99 bg_BG.utf8
 100 br_FR
 101 bs_BA
 102 C
 103 ca_ES
 104 ca_ES@euro
 105 ca_ES.utf8
 106 ca_ES.utf8@euro
 107 cs_CZ
 108 cs_CZ.utf8
 109 cy_GB
 110 da_DK
 111 da_DK.iso885915
 112 da_DK.utf8
 113 de_AT
 114 de_AT@euro
 115 de_AT.utf8
 116 de_AT.utf8@euro
 117 de_BE
 118 de_BE@euro
 119 de_BE.utf8
 120 de_BE.utf8@euro
 121 de_CH
 122 de_CH.utf8
 123 de_DE
 124 de_DE@euro
 125 de_DE.utf8
 126 de_DE.utf8@euro
 127 de_LU
 128 de_LU@euro
 129 de_LU.utf8
 130 de_LU.utf8@euro
 131 el_GR
 132 el_GR.utf8
 133 en_AU
 134 en_AU.utf8
 135 en_BW
 136 en_BW.utf8
 137 en_CA
 138 en_CA.utf8
 139 en_DK
 140 en_DK.utf8
 141 en_GB
 142 en_GB.iso885915
 143 en_GB.utf8
 144 en_HK
 145 en_HK.utf8
 146 en_IE
 147 en_IE@euro
 148 en_IE.utf8
 149 en_IE.utf8@euro
 150 en_IN
 151 en_NZ
 152 en_NZ.utf8
 153 en_PH
 154 en_PH.utf8
 155 en_SG
 156 en_SG.utf8
 157 en_US
 158 en_US.iso885915
 159 en_US.utf8
 160 en_ZA
 161 en_ZA.utf8
 162 en_ZW
 163 en_ZW.utf8
 164 es_AR
 165 es_AR.utf8
 166 es_BO
 167 es_BO.utf8
 168 es_CL
 169 es_CL.utf8
 170 es_CO
 171 es_CO.utf8
 172 es_CR
 173 es_CR.utf8
 174 es_DO
 175 es_DO.utf8
 176 es_EC
 177 es_EC.utf8
 178 es_ES
 179 es_ES@euro
 180 es_ES.utf8
 181 es_ES.utf8@euro
 182 es_GT
 183 es_GT.utf8
 184 es_HN
 185 es_HN.utf8
 186 es_MX
 187 es_MX.utf8
 188 es_NI
 189 es_NI.utf8
 190 es_PA
 191 es_PA.utf8
 192 es_PE
 193 es_PE.utf8
 194 es_PR
 195 es_PR.utf8
 196 es_PY
 197 es_PY.utf8
 198 es_SV
 199 es_SV.utf8
 200 es_US
 201 es_US.utf8
 202 es_UY
 203 es_UY.utf8
 204 es_VE
 205 es_VE.utf8
 206 et_EE
 207 et_EE.utf8
 208 eu_ES
 209 eu_ES@euro
 210 eu_ES.utf8
 211 eu_ES.utf8@euro
 212 fa_IR
 213 fi_FI
 214 fi_FI@euro
 215 fi_FI.utf8
 216 fi_FI.utf8@euro
 217 fo_FO
 218 fo_FO.utf8
 219 fr_BE
 220 fr_BE@euro
 221 fr_BE.utf8
 222 fr_BE.utf8@euro
 223 fr_CA
 224 fr_CA.utf8
 225 fr_CH
 226 fr_CH.utf8
 227 fr_FR
 228 fr_FR@euro
 229 fr_FR.utf8
 230 fr_FR.utf8@euro
 231 fr_LU
 232 fr_LU@euro
 233 fr_LU.utf8
 234 fr_LU.utf8@euro
 235 ga_IE
 236 ga_IE@euro
 237 ga_IE.utf8
 238 ga_IE.utf8@euro
 239 gl_ES
 240 gl_ES@euro
 241 gl_ES.utf8
 242 gl_ES.utf8@euro
 243 gv_GB
 244 gv_GB.utf8
 245 he_IL
 246 he_IL.utf8
 247 hi_IN
 248 hr_HR
 249 hr_HR.utf8
 250 hu_HU
 251 hu_HU.utf8
 252 id_ID
 253 id_ID.utf8
 254 is_IS
 255 is_IS.utf8
 256 it_CH
 257 it_CH.utf8
 258 it_IT
 259 it_IT@euro
 260 it_IT.utf8
 261 it_IT.utf8@euro
 262 iw_IL
 263 iw_IL.utf8
 264 ja_JP.eucjp
 265 ja_JP.utf8
 266 ka_GE
 267 kl_GL
 268 kl_GL.utf8
 269 ko_KR.euckr
 270 ko_KR.utf8
 271 kw_GB
 272 kw_GB.utf8
 273 lt_LT
 274 lt_LT.utf8
 275 lv_LV
 276 lv_LV.utf8
 277 mi_NZ
 278 mk_MK
 279 mk_MK.utf8
 280 mr_IN
 281 ms_MY
 282 ms_MY.utf8
 283 mt_MT
 284 mt_MT.utf8
 285 nl_BE
 286 nl_BE@euro
 287 nl_BE.utf8
 288 nl_BE.utf8@euro
 289 nl_NL
 290 nl_NL@euro
 291 nl_NL.utf8
 292 nl_NL.utf8@euro
 293 nn_NO
 294 nn_NO.utf8
 295 no_NO
 296 no_NO.utf8
 297 oc_FR
 298 pl_PL
 299 pl_PL.utf8
 300 POSIX
 301 pt_BR
 302 pt_BR.utf8
 303 pt_PT
 304 pt_PT@euro
 305 pt_PT.utf8
 306 pt_PT.utf8@euro
 307 ro_RO
 308 ro_RO.utf8
 309 ru_RU
 310 ru_RU.koi8r
 311 ru_RU.utf8
 312 ru_UA
 313 ru_UA.utf8
 314 se_NO
 315 sk_SK
 316 sk_SK.utf8
 317 sl_SI
 318 sl_SI.utf8
 319 sq_AL
 320 sq_AL.utf8
 321 sr_YU
 322 sr_YU@cyrillic
 323 sr_YU.utf8
 324 sr_YU.utf8@cyrillic
 325 sv_FI
 326 sv_FI@euro
 327 sv_FI.utf8
 328 sv_FI.utf8@euro
 329 sv_SE
 330 sv_SE.iso885915
 331 sv_SE.utf8
 332 ta_IN
 333 te_IN
 334 tg_TJ
 335 th_TH
 336 th_TH.utf8
 337 tl_PH
 338 tr_TR
 339 tr_TR.utf8
 340 uk_UA
 341 uk_UA.utf8
 342 ur_PK
 343 uz_UZ
 344 vi_VN
 345 vi_VN.tcvn
 346 wa_BE
 347 wa_BE@euro
 348 yi_US
 349 zh_CN
 350 zh_CN.gb18030
 351 zh_CN.gbk
 352 zh_CN.utf8
 353 zh_HK
 354 zh_HK.utf8
 355 zh_TW
 356 zh_TW.euctw
 357 zh_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">
 362 LANG=en_US
 363 LC_CTYPE="en_US"
 364 LC_NUMERIC="en_US"
 365 LC_TIME="en_US"
 366 LC_COLLATE="en_US"
 367 LC_MONETARY="en_US"
 368 LC_MESSAGES="en_US"
 369 LC_PAPER="en_US"
 370 LC_NAME="en_US"
 371 LC_ADDRESS="en_US"
 372 LC_TELEPHONE="en_US"
 373 LC_MEASUREMENT="en_US"
 374 LC_IDENTIFICATION="en_US"
 375 LC_ALL=
 376 </pre></blockquote></div></li></ul></div><p>
 377 From Josuttis, p. 697-698, which says, that "there is only *one*
 378 relation (of the C++ locale mechanism) to the C locale mechanism: the
 379 global C locale is modified if a named C++ locale object is set as the
 380 global 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="idm269891582432"></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="idm269891577664"></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="idm269891574576"></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="idm269891572288"></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="idm269891570016"></a><p><span class="title"><em>
 417         <a class="link" href="http://www.opengroup.org/austin/" 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="idm269891566784"></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="idm269891562160"></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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