Circular dependency caught in sort_variables only String type

GNU Radio
1

Hi,

I’m getting this error with string type variables using gnuradio 3.7.5
and
I cannot figure out how to solve it. I’m using a normal variable plus a
config variable in this way:

Variable:
id: variable_A
value: config_variable_A

Variable Config:
id: config_variable_A
…
WriteBack: variable_A

This way the variable reads the config file at the start and the
variable
config writes the latest value of the variable at the end. It works very
well with Integers.

When I change the Config variable type to “String” and I generate the
flow
graph, I get the error:

Generate Error: circular dependency caught in sort_variables

Could anyone please help me to get this behaviour for a String type
variable please?

Thank you,
Murray

2

On Mon, Oct 6, 2014 at 4:39 AM, Murray T.
[email protected]
wrote:

Variable Config:
graph, I get the error:

Generate Error: circular dependency caught in sort_variables

Could anyone please help me to get this behaviour for a String type
variable please?

Thank you,
Murray

Yeah, this is a fundamental issue with the way that the GRC templates
are
formatted and described. The circular issue has come up rarely in the
past,
but it’s certainly been a problem for me here and there.

Tom

3

Thanks for your comments,

Is there an open issue for this problem? Is this a bug or am I doing
something that I shouldn’t?
I cannot hard-code the string because I need to be able to change the IP
address of a UDP Sink block.

Thanks,
Murray

4

I ran into this just last week, trying to have editable text fields for
configuration information (“hackrf=0”, “rtl=0”, …) that would be store
in
the config block. I ended up punting on the issue, and just hard-coding
those strings into my flow graph. Glad to know it wasn’t something I did
wrong.

5

On Tue, Oct 7, 2014 at 8:14 AM, Murray T.
[email protected]
wrote:

Thanks for your comments,

Is there an open issue for this problem? Is this a bug or am I doing
something that I shouldn’t?
I cannot hard-code the string because I need to be able to change the IP
address of a UDP Sink block.

Thanks,
Murray

It’s not really a bug since it’s part of the design of the variables.
However, it could be a feature in a future release of GRC. We’re working
on
overhauling GRC in a number of ways that might help us better support
this.
Instead of making this an Issue in our Issue tracker, probably better
for
the GRC Roadmap:

http://gnuradio.org/redmine/projects/gnuradio/wiki/GRCroadmap

Thanks,
Tom

6

Thanks for the explanation Tom.

Regards,
Murray