Martin, Yes, pop them outside the block, but also outside of the flow graph. Exactly reverse of the last example "Posting from External Sources" here:
http://gnuradio.org/doc/doxygen/page_msg_passing.html "The last feature of the message passing architecture to discuss here is how it can be used to take in messages from an external source. We can call a block's gr::basic_block::_post method directly and pass it a message. So any block with an input message port can receive messages from the outside in this way." I want to take any block with an output message port and _pull that message to the outside (of the flow so I can process it in Python). Presently, with the old queued messaging system, I can use blocks.message_sink() to take an item into a message queue I can access outside the flow. Since this will be deprecated, I'd want to use blocks.tagged_stream_to_pdu() to generate a message, but don't see a way to get those messages stored into a FIFO (queue) and access them outside the flow. As you suggest, maybe the solution is to develop a block, with an input message port, that performs the callback and stores those messages in a FIFO. From browsing the documentation, it looks like the message_debug block will store up messages (I haven't attempted to read those messages), but I'd be worried about overflows. I guess the ideal was to do it without developing or modifying any blocks. Though looking at line 278 of usrp_spectrum_sense.py, when the message queues are deprecated, what would you do to get the data out of the flow? I assume blocks.bin_statistics_f() would have to be re-written to have a message port output, but then how do you get that message out of the flow? https://github.com/gnuradio/gnuradio/blob/master/gr-uhd/examples/python/usrp_spectrum_sense.py#L278 Thanks, Lou Martin Braun-2 wrote > So you want pop messages from outside the block, right? Is the original > block written in C++? > > delete_head_block() should work, but this seems unusual. Typically, we > have two mechanisms of handling messages: Dedicated message handler > callbacks, or we pop the queue ourselves in work() using delete_head(). > > If you're popping messages outside of the block, the block itself would > never see or use those messages -- which is why I'm surprised. You might > be better of writing a mini-Python-block that handles the messages. > > Cheers, > M -- View this message in context: http://gnuradio.4.n7.nabble.com/Insert-messages-in-queues-tp53272p53279.html Sent from the GnuRadio mailing list archive at Nabble.com. _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
