Re: [Discuss-gnuradio] Dynamically changing the flowgraph

[Ilia Mirkin]

On Sun, 2005-10-23 at 11:09 -0700, Eric Blossom wrote:
> On Sun, Oct 23, 2005 at 09:35:58AM +0530, Ramakrishnan Muthukrishnan wrote:
> > 
> > Folks,
> > 
> > I am trying to implement a GUI frontend for the little Softrock40 board
> > from amqrp. I have a very primitive but usable radio up and running. 
> > 
> > This is what I am trying to do. On the click of a button, the user
> > should be able to switch from a FFT view to waterfall view. To do this,
> > I stopped the flow_graph, disconnected the waterfall block and connect
> > FFT block (or vice-versa), and start the flow_graph again. But the
> > problem is that the block disconnected remain dangling and has to be
> > distroyed completely from the instance, otherwise it gives an error.
> > 
> > This is what I am trying. I need to change it to use the new fftsink
> > usage. Any idea how to fix this? 
> 
> I think you're on the right track.  Does the code below work OK?
> That is, if you drop the reference to waterfall_block, does it work
> OK.  
> 
> What's happening is that the underlying hierarchical block remains
> partially connected (internally), and then the sanity checker
> complains that it doesn't have inputs or outputs connected when you
> try to restart.

Why is it even making sure that everything is connected up properly? If
it's not, it should just not call its work function... (I realize that
the answer is 'because it's coded that way' but I'm hoping to see if
there is a more rational explanation.)

Ilia