# Help needed with hacking through SWIG / Python / custom block

**URL:** <https://www.ruby-forum.com/t/help-needed-with-hacking-through-swig-python-custom-block/233115>\
**Category:** GNU Radio\
**Created:** [November 18, 2014, 3:56pm UTC](https://www.ruby-forum.com/t/help-needed-with-hacking-through-swig-python-custom-block/233115 "2014-11-18T15:56:24Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![addis\_a](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/c4cdca/32.png) [@addis\_a](https://www.ruby-forum.com/u/addis_a)\
**Post date:** [November 18, 2014, 3:56pm UTC](https://www.ruby-forum.com/t/help-needed-with-hacking-through-swig-python-custom-block/233115/1 "2014-11-18T15:56:24Z")

</div>

Hi all,

I’m trying a sort of a ‘hack’, but it doesn’t work so far. What I want  
to do is to add a method to the class in my custom block, and make this  
method available in Python (the top\_block.py). Without knowledge of SWIG  
I just tried the following things (where ZZZ is the name of my block):

1. Add the method protoype to ZZZ.h
2. Add the method protoype to ZZZ\_impl.h
3. Implement the method in ZZZ\_impl.cc
4. Empty the build/swig folder to force a swig rebuild
5. Run make again

When running top\_block.py I get the following errors (apparently my goal  
is not that simple):

Traceback (most recent call last):  
File “top\_block\_modified.py”, line 16, in   
import TNO\_JJJ\_2014  
File  
“/usr/local/lib/python2.7/dist-packages/TNO\_JJJ\_2014/ **init**.py”, line  
45, in   
from TNO\_JJJ\_2014\_swig import \*  
File  
“/usr/local/lib/python2.7/dist-packages/TNO\_JJJ\_2014/TNO\_JJJ\_2014\_swig.py”,  
line 28, in   
\_TNO\_JJJ\_2014\_swig = swig\_import\_helper()  
File  
“/usr/local/lib/python2.7/dist-packages/TNO\_JJJ\_2014/TNO\_JJJ\_2014\_swig.py”,  
line 24, in swig\_import\_helper  
\_mod = imp.load\_module(’\_TNO\_JJJ\_2014\_swig’, fp, pathname,  
description)  
ImportError: /usr/local/lib/libgnuradio-TNO\_JJJ\_2014.so: undefined  
symbol: \_ZN3uhd14tune\_request\_tC1Ed

Make reported me before:

Install the project…  
– Install configuration: “Release”  
– Up-to-date:  
/usr/local/lib/cmake/TNO\_JJJ\_2014/TNO\_JJJ\_2014Config.cmake  
– Up-to-date: /usr/local/include/TNO\_JJJ\_2014/api.h  
– Installing: /usr/local/include/TNO\_JJJ\_2014/JJJ\_kernel.h  
– Installing: /usr/local/lib/libgnuradio-TNO\_JJJ\_2014.so  
– Installing:  
/usr/local/lib/python2.7/dist-packages/TNO\_JJJ\_2014/\_TNO\_JJJ\_2014\_swig.so  
– Removed runtime path from  
“/usr/local/lib/python2.7/dist-packages/TNO\_JJJ\_2014/\_TNO\_JJJ\_2014\_swig.so”  
– Installing:  
/usr/local/lib/python2.7/dist-packages/TNO\_JJJ\_2014/TNO\_JJJ\_2014\_swig.py  
– Installing:  
/usr/local/lib/python2.7/dist-packages/TNO\_JJJ\_2014/TNO\_JJJ\_2014\_swig.pyc  
– Installing:  
/usr/local/lib/python2.7/dist-packages/TNO\_JJJ\_2014/TNO\_JJJ\_2014\_swig.pyo  
– Up-to-date:  
/usr/local/include/TNO\_JJJ\_2014/TNO\_JJJ\_2014/swig/TNO\_JJJ\_2014\_swig.i  
– Installing:  
/usr/local/include/TNO\_JJJ\_2014/TNO\_JJJ\_2014/swig/TNO\_JJJ\_2014\_swig\_doc.i  
– Up-to-date:  
/usr/local/lib/python2.7/dist-packages/TNO\_JJJ\_2014/ **init**.py  
– Up-to-date:  
/usr/local/lib/python2.7/dist-packages/TNO\_JJJ\_2014/ **init**.pyc  
– Up-to-date:  
/usr/local/lib/python2.7/dist-packages/TNO\_JJJ\_2014/ **init**.pyo  
– Up-to-date:  
/usr/local/share/gnuradio/grc/blocks/TNO\_JJJ\_2014\_JJJ\_kernel.xml

Anybody knows what I have to add/change to get this working? Maybe  
something in the **init**.py file? If so, how do I generate the  
corresponding .pyc and .pyo files?

Best regards,

Jeroen

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