Re: [Discuss-gnuradio] Multiple C files required by single C++ block.How to build?

['Eric Blossom']

> From: Jonas Hodel [mailto:address@hidden 
> Sent: Wednesday, November 29, 2006 1:05 PM
> To: Eric Blossom
> Cc: address@hidden
> Subject: Re: [Discuss-gnuradio] Multiple C files required by single C++
> block.How to build?
> 
> 
> Hello,
> 
> Thanks to both Eric and Daniel for your prompt help.
> 
> Yes this does make sense and it was the first thing I tried. After it didn't
> work with my files I went right back to basics (I am building a la
> gr-howto-write-a-block). I created very simple .h/.c files as a test.
> 
> Then:
> Within "howto_square2_ff.h" I added #include "test.h".
> Within  "howto_square2_ff.cc" I added a call to jonas_test(), located in the
> constructor howto_square2_ff ().
> I added test.c to the "_howto_la_SOURCES" entry in "src/lib/Makefile.am".
> 
> Finally: "make clean", "make" and "make check".
> 
> This results in:
> 
> ImportError:
> /home/jonas/gnuradio/gr-howto-write-a-block-3.0.2/src/lib/.libs/_howto.so:
> undefined symbol: _Z10jonas_testv

This is because you included a C .h file into a C++ source file.
The compiler assumed (since you didn't tell it otherwise) that 
jonas_test was a C++ function.  Thus the name mangling.

The fix is to surround the inclusion of the C include file with:

extern "C" {
#include "jonas_test.h"
}

FWIW, this is standard C++, and has nothing to do with GNU Radio, SWIG
or Python.

Eric