PCH-less compilation fix

[wxWidgets.git] / docs / doxygen / overviews / changes_since28.h

diff --git a/docs/doxygen/overviews/changes_since28.h b/docs/doxygen/overviews/changes_since28.h
index 0f7846ccdb7b50c77025fa3f490b6f2d5d5f448f..b8b087624e05bce9a9319d8677a1ddc03e4761e0 100644 (file)
--- a/docs/doxygen/overviews/changes_since28.h
+++ b/docs/doxygen/overviews/changes_since28.h
@@ -46,6 +46,22 @@ passing it to @c printf() will now result in a crash. It is strongly advised to
 recompile your code with a compiler warning about passing non-POD objects to
 vararg functions, such as g++.
 
 recompile your code with a compiler warning about passing non-POD objects to
 vararg functions, such as g++.
 

+The change of the type of wxString::c_str() can also result in compilation
+errors when passing its result to a function overloaded to take both narrow and
+wide strings and in this case you must select the version which you really want
+to use, e.g.:
+@code
+    void OpenLogFile(const char *filename);
+    void OpenLogFile(const wchar_t *filename);
+
+    wxString s;
+    OpenLogFile(s);             // ERROR: ambiguity
+    OpenLogFile(s.c_str());     // ERROR: ambiguity
+    OpenLogFile(s.wx_str());    // OK: function called depends on the build
+    OpenLogFile(s.mb_str());    // OK: always calls narrow string overload
+    OpenLogFile(s.wc_str());    // OK: always calls wide string overload
+@endcode
+

 The other class of incompatible changes is due to modifying some virtual
 methods to use @c wxString parameters instead of @c const @c wxChar* ones to
 make them accept both narrow and wide strings. This is not a problem if you
 The other class of incompatible changes is due to modifying some virtual
 methods to use @c wxString parameters instead of @c const @c wxChar* ones to
 make them accept both narrow and wide strings. This is not a problem if you


@@ -93,5 +109,49 @@ Finally, a few structure fields, notable @c wxCmdLineEntryDesc::shortName,
   your code if you overrode these functions and change the functions in the
   derived classes to use const reference as well.
 
   your code if you overrode these functions and change the functions in the
   derived classes to use const reference as well.
 

+- Calling wxConfig::Write() with an enum value will fail to compile because
+  wxConfig now tries to convert all unknown types to wxString automatically
+  using wxToString() function.
+
+  The simplest solution is to cast the enum value to int, e.g.
+  @code
+    enum Colour { Red, Green, Blue };
+
+    wxConfig conf;
+    conf.Write("MyFavouriteColour", Red);       // ERROR: no match
+    conf.Write("MyFavouriteColour", int(Red));  // OK
+  @endcode
+
+  Another possibility which exists now is to provide an overload of
+  wxToString() (and wxFromString()) for your own type, e.g.
+
+  @code
+    wxString wxToString(Colour col)
+    {
+        return col == Red ? "R" : col == Green ? "G" : "B";
+    }
+
+    bool wxFromString(const wxString& s, Colour* col)
+    {
+        if ( s.length() != 1 )
+            return false;
+
+        switch ( s[0].GetValue() )
+        {
+            case 'R': *col = Red; return true;
+            case 'G': *col = Green; return true;
+            case 'B': *col = Blue; return true;
+        }
+
+        return false;
+    }
+  @endcode
+
+  Of course, this will change the format of the wxConfig output which may be
+  undesirable.
+
+- wxTE_AUTO_SCROLL style is deprecated as it's always on by default anyhow in
+  the ports which support it so you should simply remove any mentions of it
+  from your code.

 */
 
 */