[Python-Dev] unicode objects and C++

[M.-A. Lemburg]

Mark Hammond wrote:
> 
> I struck a bit of a snag with the Unicode support when trying to use the
> most recent update in a C++ source file.
> 
> The problem turned out to be that unicodeobject.h did a #include "wchar.h",
> but did it while an 'extern "C"' block was open.  This upset the MSVC6
> wchar.h, as it has special C++ support.

Thanks for reporting this.
 
> Attached below is a patch I made to unicodeobject.h that solved my problem
> and allowed my compilations to succeed.  Theoretically the same problem
> could exist for wctype.h, and probably lots of other headers, but this is
> the immediate problem :-)
> 
> An alternative patch would be to #include "whcar.h" in PC\config.h outside
> of any 'extern "C"' blocks - wchar.h on Windows has guards that allows for
> multiple includes, so the unicodeobject.h include of that file will succeed,
> but not have the side-effect it has now.
> 
> Im not sure what the preferred solution is - quite possibly the PC\config.h
> change, but Ive include the unicodeobject.h patch anyway :-)
> 
> Mark.
> 
> *** unicodeobject.h     2000/03/13 23:22:24     2.2
> --- unicodeobject.h     2000/03/14 01:06:57
> ***************
> *** 85,91 ****
> --- 85,101 ----
>   #endif
> 
>   #ifdef HAVE_WCHAR_H
> +
> + #ifdef __cplusplus
> + } /* Close the 'extern "C"' before bringing in system headers */
> + #endif
> +
>   # include "wchar.h"
> +
> + #ifdef __cplusplus
> + extern "C" {
> + #endif
> +
>   #endif
> 
>   #ifdef HAVE_USABLE_WCHAR_T
> 

I've included this patch (should solve the problem for all inlcuded
system header files, since it wraps only the Unicode 
APIs in extern "C"):

--- /home/lemburg/clients/cnri/CVS-Python/Include/unicodeobject.h       Fri Mar 10 23:33:05 2000
+++ unicodeobject.h     Tue Mar 14 10:38:08 2000
@@ -1,10 +1,7 @@
 #ifndef Py_UNICODEOBJECT_H
 #define Py_UNICODEOBJECT_H
-#ifdef __cplusplus
-extern "C" {
-#endif
 
 /*
 
 Unicode implementation based on original code by Fredrik Lundh,
 modified by Marc-Andre Lemburg (mal@lemburg.com) according to the
@@ -167,10 +165,14 @@ typedef unsigned short Py_UNICODE;
 
 #define Py_UNICODE_MATCH(string, offset, substring)\
     (!memcmp((string)->str + (offset), (substring)->str,\
              (substring)->length*sizeof(Py_UNICODE)))
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /* --- Unicode Type ------------------------------------------------------- */
 
 typedef struct {
     PyObject_HEAD
     int length;                        /* Length of raw Unicode data in buffer */


I'll post a complete Unicode update patch by the end of the week
for inclusion in CVS.

-- 
Marc-Andre Lemburg
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