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

[Nowlan, Sean]

From: discuss-gnuradio-bounces+address@hidden [mailto:discuss-gnuradio-bounces+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?