On Thu, Dec 5, 2019 at 1:04 AM Müller, Marcus (CEL) <
address@hidden> wrote:
However, with your zero in- and output hier block, top_block.connect(something) was *never* called with the hier block, and hence, the hier block didn't become part of a flow graph that is to be executed. It's just a graph that *exists*, not one that *does* something.
TL;DR: can't use a hier block without outside connections, since that's not becoming part of the top_block that'll be executed.
In addition to the usual connect() that takes two blocks, there is also a connect() method overload that takes only one block, specifically to enable adding a block with no connections to a parent hier block or top block.
I just tested this case — GRC fails to generate an appropriate connect() call in the top block, but if I add one, then the blocks within the hier block execute as expected. I have filed issue
https://github.com/gnuradio/gnuradio/issues/2950 about this.