[Discuss-gnuradio] passing USRP source block shared pointer through SWIG

[Anderson, Douglas J.]

Hi all,

I'm looking into the possibility of passing the <gr_block gr uhd usrp source (0)> object from Python into a C++ out of tree module. In my module, I have:

    controller_cc_impl::controller_cc_impl(gr::uhd::usrp_source::sptr usrp, [...])

I get a TypeError when I instantiate the block. It seems like the object created in Python is not a proxy for the sptr, and I can't figure out quite how to get access to the sptr from Python.

I've tried both of the alternatives to passing back in the sptr: I've tried sending commands to the USRP via message passing interface, but only freq and gain are implemented. At the very least I need the full tune_request capability.

I've also tried making that call with fevall_dd, but it's a blocking call and it's too slow for my application. I could maybe spawn that call in its own thread so it doesn't block, but I think passing the shared pointer back is the cleaner and more correct solution.

So, how hard is this going to be? SWIG 2.0 supports boost's shared pointer. I'm wondering if it'd just be a few extra lines in GR_SWIG_BLOCK_MAGIC2 to expose it, or am I kidding myself?

http://www.swig.org/Doc2.0/Library.html#Library_std_shared_ptr

Thanks in advance,

-Doug