redesign PBD::LocaleGuard to work correctly (i.e. not break translations)

diff --git a/libs/pbd/locale_guard.cc b/libs/pbd/locale_guard.cc
index b4225d38758359f08f1c8d02074f4c97b9ffa874..f5f97f20423c400f78079358236e69fb494ed0b0 100644 (file)
--- a/libs/pbd/locale_guard.cc
+++ b/libs/pbd/locale_guard.cc
@@ -29,54 +29,72 @@
 
 using namespace PBD;
 
-/* The initial C++ locale is "C" regardless of the user's preferred locale.
- * The C locale from setlocale() matches the user's preferred locale
+/* Neither C nor C++ pick up a user's preferred locale choice without the
+ * application actively taking steps to make this happen.
+ *
+ * For C: setlocale (LC_ALL, "");
+ * For C++ (assuming that the C version was called):
+ *      std::locale::global (std::locale (setlocale (LC_ALL, 0)));
+ *
+ * The application needs to make these calls, probably in main().
  *
  * Setting the C++ locale will change the C locale, but not the other way 'round.
  * and some plugin may change either behind our back.
  */
 
 LocaleGuard::LocaleGuard ()
-       : old_c (0)
+       : old_c_locale (0)
 {
-       char* actual = setlocale (LC_NUMERIC, NULL);
-       if (strcmp ("C", actual)) {
-               DEBUG_TRACE (DEBUG::Locale, string_compose ("LG: change locale from '%1' to 'C'\n", actual));
-               /* purpose of LocaleGuard is to make sure we're using "C" for
-                  the numeric locale during its lifetime, so make it so.
-               */
-               old_c = strdup (actual);
-               /* this changes both C++ and C locale */
-               std::locale::global (std::locale (std::locale::classic(), "C", std::locale::numeric));
-       }
-       if (old_cpp != std::locale::classic ()) {
-               PBD::error << "LocaleGuard: initial C++ locale is not 'C'. Expect non-portable session files.\n";
-               DEBUG_TRACE (DEBUG::Locale, "LG: initial C++ locale is not 'C'. Expect non-portable session files.\n");
+       /* A LocaleGuard object ensures that the
+        * LC_NUMERIC/std::locale::numeric aspect of the C and C++ locales are
+        * set to "C" during its lifetime, so that printf/iostreams use a
+        * portable format for numeric output (i.e. 1234.5 is always 1234.5 and
+        * not sometimes 1234,5, as it would be in fr or de locales)
+        */
+
+       char const * const current_c_locale = setlocale (LC_NUMERIC, 0);
+
+       if (strcmp ("C", current_c_locale) != 0) {
+
+               old_c_locale = strdup (current_c_locale);
+
+               /* set the C++ global/default locale to whatever we are using
+                * now, but with "C" numeric handling.
+                *
+                * this also sets the C locale, so no call to setlocale() is required.
+                */
+
+               std::locale::global (std::locale (old_cpp_locale, "C", std::locale::numeric));
+               pre_cpp_locale = std::locale();
+
+               DEBUG_TRACE (DEBUG::Locale, string_compose ("LG: change locale from '%1' => %2\n", old_cpp_locale.name(), pre_cpp_locale.name()));
        }
 }
 
 LocaleGuard::~LocaleGuard ()
 {
-       char* actual = setlocale (LC_NUMERIC, NULL);
-       std::locale current;
+       char const * current_c_locale = setlocale (LC_NUMERIC, 0);
+       std::locale current_cpp_locale;
 
-       if (current != old_cpp) {
-               /* the C++ locale should always be "C", that's the default
-                * at application start, and ardour never changes it to
-                * anything but "C".
-                *
-                * if it's not: some plugin meddled with it.
-                */
-               if (old_cpp != std::locale::classic ()) {
-                       PBD::error << "LocaleGuard: someone (a plugin) changed the C++ locale, expect non-portable session files.\n";
-                       DEBUG_TRACE (DEBUG::Locale, "LG: someone (a plugin) changed the C++ locale, expect non-portable session files.\n");
-               }
-               std::locale::global (old_cpp);
-               DEBUG_TRACE (DEBUG::Locale, string_compose ("LG: restore C++ locale: '%1'\n", old_cpp.name ()));
-       }
-       if (old_c && strcmp (old_c, actual)) {
-               setlocale (LC_NUMERIC, old_c);
-               DEBUG_TRACE (DEBUG::Locale, string_compose ("LG: restore C locale: '%1'\n", old_c));
+       if (current_cpp_locale != pre_cpp_locale) {
+
+               PBD::error << string_compose ("LocaleGuard: someone (a plugin) changed the C++ locale from\n\t%1\nto\n\t%2\n, expect non-portable session files. Decimal OK ? %2",
+                                             old_cpp_locale.name(), current_cpp_locale.name(),
+                                             (std::use_facet<std::numpunct<char> >(std::locale()).decimal_point() == '.'))
+                          << endmsg;
+               DEBUG_TRACE (DEBUG::Locale, string_compose ("LG: someone (a plugin) changed the C++ locale (Decimal OK ? '%1'); expect non-portable session files.\n",
+                                                           (std::use_facet<std::numpunct<char> >(std::locale()).decimal_point() == '.')));
+
+               /* this resets C & C++ locales */
+               std::locale::global (old_cpp_locale);
+               DEBUG_TRACE (DEBUG::Locale, string_compose ("LG: restore C & C++ locale: '%1'\n", std::locale().name()));
+
+       } else if (old_c_locale && (strcmp (current_c_locale, old_c_locale) != 0)) {
+
+               /* reset only the C locale */
+               setlocale (LC_NUMERIC, old_c_locale);
+               DEBUG_TRACE (DEBUG::Locale, string_compose ("LG: restore C locale from %1 to\n'%2'\n(C++ is '%3')\n", current_c_locale, old_c_locale, std::locale().name()));
        }
-       free (old_c);
+
+       free (const_cast<char*> (old_c_locale));
 }

diff --git a/libs/pbd/pbd/locale_guard.h b/libs/pbd/pbd/locale_guard.h
index 3342603f2061644830af2b33db9b41b2609d63ab..b10e4d3ee3e216ccd81511156da23f2f21366303 100644 (file)
--- a/libs/pbd/pbd/locale_guard.h
+++ b/libs/pbd/pbd/locale_guard.h
@@ -26,15 +26,16 @@
 
 namespace PBD {
 
-       struct LIBPBD_API LocaleGuard {
-               public:
-                       LocaleGuard ();
-                       ~LocaleGuard ();
-
-               private:
-                       std::locale old_cpp;
-                       char* old_c;
-       };
+struct LIBPBD_API LocaleGuard {
+  public:
+       LocaleGuard ();
+       ~LocaleGuard ();
+
+  private:
+       std::locale old_cpp_locale;
+       std::locale pre_cpp_locale;
+       char const * old_c_locale;
+};
 }
 
 #endif /* __pbd_locale_guard__ */