Switch to boost::format for non-trivial substitution of values into

user-visible strings.

This makes it easier to translate the patterns.  See the comment added
to src/util/gettext.hpp .

SVN-Revision: 6634

INSTALL

@@ -64,7 +64,7 @@ REQUIREMENTS
 * GLEW
     http://glew.sourceforge.net/
 
-* Boost's smart_ptr headers
+* Boost's smart_ptr and format headers
     http://www.boost.org/
 
   Note: We tried to write our code clean, portable and platform neutral, so it

src/supertux/levelintro.cpp

@@ -26,6 +26,7 @@
 #include "util/gettext.hpp"
 
 #include <sstream>
+#include <boost/format.hpp>
 
 LevelIntro::LevelIntro(const Level* level, const Statistics* best_level_statistics) :
   level(level), 
@@ -90,7 +91,7 @@ LevelIntro::draw(DrawingContext& context)
 
   std::string author = level->get_author();
   if ((author != "") && (author != "SuperTux Team")) {
-    std::string author_text = std::string(_("contributed by ")) + author;
+    std::string author_text = str(boost::format(_("contributed by %s")) % author);
     context.draw_center_text(Resources::small_font, author_text, Vector(0, py), LAYER_FOREGROUND1, LevelIntro::author_color);
     py += static_cast<int>(Resources::small_font->get_height());
   }

src/supertux/main.cpp

@@ -22,6 +22,7 @@
 #include <iostream>
 #include <binreloc.h>
 #include <tinygettext/log.hpp>
+#include <boost/format.hpp>
 
 #include "supertux/main.hpp"
 
@@ -227,8 +228,10 @@ Main::init_physfs(const char* argv0)
 void
 Main::print_usage(const char* argv0)
 {
-  std::cerr << _("Usage: ") << argv0 << _(" [OPTIONS] [LEVELFILE]\n\n")
-            << _("Options:\n"
+  std::cerr << boost::format(_(
+                 "\n"
+                 "Usage: %s [OPTIONS] [LEVELFILE]\n\n"
+                 "Options:\n"
                  "  -f, --fullscreen             Run in fullscreen mode\n"
                  "  -w, --window                 Run in window mode\n"
                  "  -g, --geometry WIDTHxHEIGHT  Run SuperTux in given resolution\n"
@@ -246,7 +249,9 @@ Main::print_usage(const char* argv0)
                  "  --record-demo FILE LEVEL     Record a demo to FILE\n"
                  "  --play-demo FILE LEVEL       Play a recorded demo\n"
                  "  -s, --debug-scripts          Enable script debugger.\n"
-                 "\n")
+                 "\n"
+                 ))
+            % argv0
             << std::flush;
 }
 

src/util/gettext.hpp

@@ -22,6 +22,25 @@
 
 #include "supertux/globals.hpp"
 
+/*
+ * If you need to do a nontrivial substitution of values into a pattern, use
+ * boost::format rather than an ad-hoc concatenation.  That way, translators can
+ * translate the format string as a whole (and even rearrange the values if
+ * necessary with "%1$s"-style codes) instead of multiple pieces.  Patterns like
+ * "Label: %s" with only one string piece are a borderline case where
+ * boost::format is not really necessary.
+ *
+ * http://www.mihai-nita.net/article.php?artID=20060430a
+ *
+ * Bad:
+ *     std::string msg = _("You collected ") + num + _(" coins");
+ *     std::cout << _("You collected ") << num << _(" coins");
+ * Good:
+ *     #include <boost/format.hpp>
+ *     std::string msg = str(boost::format(_("You collected %d coins")) % num);
+ *     std::cout << boost::format(_("You collected %d coins")) % num;
+ */
+
 static inline std::string _(const std::string& message)
 {
   if (dictionary_manager)