Re: [Discuss-gnuradio] GRC QT widget call function upon value change?

[Marcus D. Leech]

On 04/21/2018 04:20 PM, Louis Brown wrote:
> Is there a way to make a GRC widget, such as the QT GUI Chooser, call 
> a function when it changes value?
>
> I have some serial port writing functions defined in a Python Module 
> block.  I set the GUI Chooser options to write_serial(0), 
> write_serial(1), etc..  The problem is the functions are evaluated 
> only once during top_block execution, not when the Chooser value is 
> changed.
>
> I have tried a Function Probe to pass the Chooser value to my 
> write_serial() once a second, but the Function Probe does not update 
> with the new Chooser value.
>
> Is there some trick to this?
>
> Thanks,
> Lou
Leverage the dependency evaluator.

Let's say your choose widget is called "foo".

Create a variable, "bar", in the value field:

your_function(foo)

Every time time that foo changes, it'll call your_function(foo), to 
satisfy the dependency that "bar" has on "foo".