[Discuss-gnuradio] GNU-Radio Companion Python flowgraph - return signal that it is finished?

[Andrew Payne]

Hello,

I am writing a program in Python to interface with a simple file
source to USRP sink flowgraph.

I have a short IQ file that I simply want to play once without
repeating, and I want the calling Python code to "know" when it's
completed after commanding the GR class instance to start via a call
to tb.start(), if tb is the class instance variable.  I came across
the C++ GR API here:
https://www.gnuradio.org/doc/doxygen/classgr_1_1block.html#a89242cb1ac9d2bf5e75f923745baa576

^ That shows there's a gr.finished() boolean return that tells you
when the flowgraph is done, but evidently .finished is not an
attribute of tb.  The only methods that worked for me are
tb.start/tb.run, tb.wait, tb.stop.

I'd also be happy with polling the GR class instance for the
noutput_items from the work function of the USRP_sink block. I know
the file size so I can have a while loop with the noutput_items value
as a condition, but how do I do that in Python?  I think I am getting
close with these 2 results from Google but still not getting it:
1) 
https://stackoverflow.com/questions/50938245/gnuradio-number-of-output-items/50943105
2) 
https://stackoverflow.com/questions/32305813/gnuradio-how-to-change-the-noutput-items-dynamically-when-writing-oot-block

Thanks,
Andrew