Re: [Discuss-gnuradio] Trouble with SWIG for packet_formatter_default child class

[Tom Rondeau]

On Tue, Feb 24, 2015 at 3:00 AM, Bastian Bloessl <address@hidden> wrote:

Hi,

I also created a custom header that derives from packet_formatter_default and this swig file works for me
https://github.com/bastibl/gr-ieee802-11/blob/master/swig/ieee802_11_swig.i

I forgot why it did it like that, but maybe it helps.

Best,
Bastian

> On 23 Feb 2015, at 22:10, Nowlan, Sean <address@hidden> wrote:
>
> From: discuss-gnuradio-bounces+sean.nowlan=address@hidden [mailto:discuss-gnuradio-bounces+sean.nowlan=address@hidden] On Behalf Of Nowlan, Sean
> Sent: Monday, February 23, 2015 3:10 PM
> To: address@hidden
> Subject: [Discuss-gnuradio] Trouble with SWIG for packet_formatter_default child class
>
> Hi all –
>
> I’m working on Tom’s packet_handling branch (github.com/trondeau/gnuradio.git) and building a custom packet formatter. Everything works in C++ land, including QA code. However, SWIG is complaining about undeclared things. I duplicated the CMake and SWIG structures of gnuradio/gr-digital/swig/ for building derived classes such as gr::digital::packet_formatter_counter. Any ideas why this would not work? Thanks!
>
> ---- first few lines of make errors ----
>
> /home/me/code/gr-myoot/build/swig/myoot_swigPYTHON_wrap.cxx: In function ‘PyObject* _wrap_packet_formatter_custom_make(PyObject*, PyObject*, PyObject*)’:
> /home/me/code/gr-myoot/build/swig/myoot_swigPYTHON_wrap.cxx:5030:3: error: ‘sptr’ was not declared in this scope
> sptr result;
> ^
> /home/me/code/gr-myoot/build/swig/myoot_swigPYTHON_wrap.cxx:5030:8: error: expected ‘;’ before ‘result’
> sptr result;
>      ^
> /home/me/code/gr-myoot/build/swig/myoot_swigPYTHON_wrap.cxx:5062:7: error: ‘result’ was not declared in this scope
>     result = gr::myoot::packet_formatter_custom::make((std::string const &)*arg1,(std::string const &)*arg2,arg3);
>     ^
>
> ---- gr-myoot/swig/myoot_swig.i ----
>
> /* -*- c++ -*- */
>
> #define MYOOT_API
>
> %include "gnuradio.i"                                    // the common stuff
> //load generated python docstrings
> %include "myoot_swig_doc.i"
> %{
> #include "myoot/packet_formatter_custom.h"
> %}
> %include "myoot/packet_formatter_custom.h"
> GR_SWIG_BLOCK_MAGIC2(myoot, packet_formatter_custom);
>
> // Properly package up non-block objects
> %include "packet_formatter_custom.i"
>
>
> ---- gr-myoot/swig/packet_formatter_custom.i ----
>
> %template(packet_formatter_custom_sptr) boost::shared_ptr<gr::myoot::packet_formatter_custom>;
> %pythoncode %{
> packet_formatter_custom_sptr.__repr__ = lambda self: "<packet_formatter_custom>"
> packet_formatter_custom = packet_formatter_custom .make;
> %}
>
> ------------------------------------------
>
> To get it to build, I added the following typedef to gr-myoot/include/myoot/packet_formatter_custom.h :
>              …
>              public:
>                              typedef boost:shared_ptr<packet_formatter_custom> sptr;
>              …
>
> Now importing SWIG-generated stuff in Python fails:
>
>>>> import myoot
> Traceback (most recent call last):
> File "<input>", line 1, in <module>
> File "/home/me/target/lib/python2.7/dist-packages/myoot/__init__.py", line 29, in <module>
>  from myoot_swig import *
> File "/home/me/target/lib/python2.7/dist-packages/myoot/myoot_swig.py", line 265, in <module>
>  packet_formatter_custom = packet_formatter_custom .make;
> AttributeError: 'function' object has no attribute 'make'
>
> This is probably due to a conflict between the definition of sptr: one is being autogenerated by SWIG based on the typedef in include/myoot/packet_formatter_custom.h; the other is the template in swig/packet_formatter_custom.i.
>
> Now if I build without the special sauce in swig/packet_formatter_custom.i, I can get “import myoot” in Python to work. However, there’s still some strange behavior if I don’t actually assign to a variable.
>
>>>> import myoot
>>>> from gnuradio import digital
>>>> formatter1 = myoot.packet_formatter_custom("1", "1", 1)
>>>> formatter2 = digital.packet_formatter_counter("1", 1)
>>>> myoot.packet_formatter_custom("1", "1", 1)
> Traceback (most recent call last):
> File "<input>", line 1, in <module>
> File "/home/me/target/lib/python2.7/dist-packages/myoot/myoot_swig.py", line 261, in <lambda>
>  packet_formatter_custom_sptr.__repr__ = lambda self: "<gr_block %s (%d)>" % (self.name(), self.unique_id())
> AttributeError: 'packet_formatter_custom_sptr' object has no attribute 'name'
>>>> digital.packet_formatter_counter("1", 1)
> <packet_formatter_default>
>
> Note that the sptr in gr-digital is of type packet_formatter_default, meaning it inherited the definition of the typedef from packet_formatter_default. In my case it didn’t work because I used GR_SWIG_BLOCK_MAGIC2 on a non block, so the __repr__ definition (above) breaks.
>
> What should I do? I can rely on GR_SWIG_BLOCK_MAGIC2, which is not really the right way to generate SWIG templates for a non block, or I can try to get things to work without redefining the sptr typedef in the child class. In that case, I need to include the proper header file (namely, packet_formatter_default.h) from gr-digital. Should I do that explicitly in myoot_swig.i, or is there a better way to add gr-digital to include dirs in swig/CMakeLists.txt?

Sean,

Did you have a look at the packet_header.i file? It's basically what Bastian figured out (maybe where he got it from). We have to do a bit more swig manipulation to get the make functions working properly.

https://github.com/trondeau/gnuradio/blob/packet_handling/gr-digital/swig/packet_header.i

Tom