Re: [Discuss-gnuradio] Discuss-gnuradio Digest, Vol 142, Issue 22

[Douglas Geiger]

This sounds like exactly the use case for stream tags (http://gnuradio.org/redmine/projects/gnuradio/wiki/BlocksCodingGuide#Stream-Tags). More info on how to use them is here: http://gnuradio.org/doc/doxygen/page_stream_tags.html

Unfortunately there isn't a good listing of tag naming conventions, so one of the best examples currently is the UHD source/sink, but for example multiple blocks understand/use the rx_freq, rx_rate or rx_time tags.

 Doug

On Mon, Sep 22, 2014 at 8:15 AM, <address@hidden> wrote:

The message passing interface works for this. I have a VITA-49 depacketizer I wrote and I used message passing to set the center frequency for QT Frequency Sink because it already has a frequency subscriber. But to use it in general, I have to change every block that needs information from the depacketizer. For example, if I want any blocks to use the sample rate supplied in the VITA-49 context packet I need to add a sample rate subscriber to everything that needs to know about it.

/\/\ark.

On Thu, 18 Sep 2014 13:45:08 -0400, Martin Braun wrote:

> This sounds like a bad idea. And no, other than violating best
> practices, there's no way to do that.
>
> What exactly are you trying to do? Would a message passing interface
> help?
>
> M
>
> On Thu, Sep 18, 2014 at 9:07 AM, <address@hidden>
> wrote:
>
> >  Is there a way to have the C++ code of a block change the value of
> a
> > variable for the rest of the flow graph?
> >
> > /\/\ark.
> > --
> > Aim for brevity while avoiding jargon.
> > ~ Edsger Dijkstra

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--
Doug Geiger
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