Re: [Discuss-gnuradio] a programming question about building a block

[Eric Blossom]

On Thu, Sep 13, 2007 at 02:54:16PM -0400, Dawei Shen wrote:
> Hey, Guys
> 
> I encountered a programming problem when I tried to build a new block. I
> defined a subclass inside my block class, which looks like:
> 
> class my_block : gr_block{
>   class my_subclass {
>      sub_class details
>   }
> }
> 
> Well, this my_subclass is part of my implementation, all its member
> functions are inline functions. Everything got compiled and installed well.
> However, when I used my block in my python script, I met some error like:
> 
> import _howto
> ImportError: /usr/local/lib/python2.5/site-packages/gnuradio/_howto.so:
> undefined symbol: _ZN22howto_my_block10my_subclass1hE
> 
> Could anybody help me with this problem? Should I do something with my .i
> file or makefile.am file?
> 
> Thank you in advance.
> 
> Dawei


SWIG doesn't deal with nested C++ classes.
This is a known limitation, and apparently hard to fix.

In your case, I doubt that the python code needs to know anything
about the implementation details, including the nested class.
I suggest trying to remove the nested class from the .i file.

Eric