Re: [Discuss-gnuradio] custom tagged_stream_block basetype and swig

[Miklos Maroti]

Hi All,

It seems that no one really has the SWIG expertise. Just to reiterate,
if I copy tagged_stream_block from GnuRadio into my OOT, and rename
it, it has the exact same compile problem. Now I wonder if GnuRadio
has some magic with the SWIG generation, maybe the base blocks are
hard coded somewhere in the generator scripts? If so, I could not find
it.

The problem seems to be that for OOT blocks deriving
tagged_stream_block the constructor is not wrapped, instead the make
is used as the block (not the implementation) still has pure virtual
functions. However, if I change the code to derive
tagged_stream_block2, then it wants to generate a constructor and of
course that fails. But why?

Best,
Miklos

On Fri, Jul 28, 2017 at 6:34 PM, Miklos Maroti <address@hidden> wrote:
> Dear All,
>
> For various reasons I am not happy with the tagged_stream_block
> implementation, and I have implemented my own version, called
> tagged_stream_block2 and put it into my OOT module. I can use the
> gr_modtool to create tagged_stream_blocks and manually change the
> basetype to my version. Everything seems to work fine, except with
> SWIG generated code. There I get undefined references error to virtual
> methods (e.g. work). However the C++ code compile fine and no such
> error is presented. In fact, before I deleted the build directory and
> rebuilt everything even GRC and SWIG was happy after a regular make.
> However, once I rebuilt everything with cmake I get these issues in
> the SWIG generated code. This is the layout:
>
> tagged_stream_block2.h goes into the include directory and listed in
> the CMakeFile.txt
> tagged_stream_block2.cc goes into the lib directory and listed in the
> CMakeFile.txt
> the swig directory CMakeFile is not changed
>
> Can anyone with SWIG expertise help? I have attached the complete error 
> message.
>
> Best,
> Miklos
>
> ~/workspace/gr-mymodule/build/swig/mymodule_swigPYTHON_wrap.cxx: In
> function ‘PyObject* _wrap_new_myblock(PyObject*, PyObject*)’:
> ~/workspace/gr-mymodule/build/swig/mymodule_swigPYTHON_wrap.cxx:44104:85:
> error: invalid new-expression of abstract class type
> ‘gr::mymodule::myblock’
>        result = (gr::mymodule::myblock *)new gr::mymodule::myblock();
>
>               ^
> In file included from
> ~/workspace/gr-mymodule/build/swig/mymodule_swigPYTHON_wrap.cxx:4412:0:
> ~/workspace/gr-mymodule/include/mymodule/myblock.h:36:20: note:
> because the following virtual functions are pure within
> ‘gr::mymodule::myblock’:
>  class MYBLOCK_API myblock : virtual public gr::tagged_stream_block2 {
>                     ^
> In file included from ~/workspace/gr-mymodule/include/mymodule/myblock.h:26:0,
>                  from
> ~/workspace/gr-mymodule/build/swig/mymodule_swigPYTHON_wrap.cxx:4412:
> ~/workspace/gr-mymodule/include/mymodule/tagged_stream_block2.h:69:3:
> note: virtual int
> gr::tagged_stream_block2::calculate_output_stream_length(const
> gr_vector_int&)
>    calculate_output_stream_length(const gr_vector_int &ninput_items) = 0;
>    ^
> ~/workspace/gr-mymodule/include/mymodule/tagged_stream_block2.h:79:15:
> note: virtual int gr::tagged_stream_block2::work(int, gr_vector_int&,
> gr_vector_const_void_star&, gr_vector_void_star&)
>    virtual int work(int noutput_items, gr_vector_int &ninput_items,
>                ^
> swig/CMakeFiles/_mymodule_swig.dir/build.make:68: recipe for target
> 'swig/CMakeFiles/_mymodule_swig.dir/mymodule_swigPYTHON_wrap.cxx.o'
> failed
> make[2]: *** 
> [swig/CMakeFiles/_mymodule_swig.dir/mymodule_swigPYTHON_wrap.cxx.o]
> Error 1
> CMakeFiles/Makefile2:237: recipe for target
> 'swig/CMakeFiles/_mymodule_swig.dir/all' failed
> make[1]: *** [swig/CMakeFiles/_mymodule_swig.dir/all] Error 2
> Makefile:138: recipe for target 'all' failed
> make: *** [all] Error 2