Adds qt-like signals to Parameters

[MarcusZuber]

I was looking for an elegant way to connect different Parameterizable-Parameters and had this idea.

This uses https://github.com/nexconnectio/pynnex which implements qt-like signals and slots and is quite light-weight. Currently, the development is quite active and looks clean.

Example:

from concert.devices.cameras.dummy import Camera
camera = await Camera()

def print_value(val):
   print(value)

camera['exposure_time'].value_set.connect(print_value)
camera.exposure = 1*q.s


exp = await CT(...)
reco = await OnlineReco(...)

exp['num_projections'].value_set.connect(reco, reco.set_number)

One motivation for this would be to couple experiment parameters with addon-parameters (the number of the online-reco couples with the num_projections of the CT experiment).

TODO:

• Tests
• Doc

[codecov]

Codecov Report

❌ Patch coverage is 93.75000% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 83.73%. Comparing base (2eb3060) to head (5bfb527).
⚠️ Report is 24 commits behind head on master.

Files with missing lines	Patch %	Lines
concert/base.py	90.90%	2 Missing ⚠️
concert/tests/unit/test_signals.py	96.15%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #548      +/-   ##
==========================================
+ Coverage   82.85%   83.73%   +0.88%     
==========================================
  Files         133      134       +1     
  Lines       10928    11022      +94     
==========================================
+ Hits         9054     9229     +175     
+ Misses       1874     1793      -81     

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[MarcusZuber]

Works only with python3.10+. 3.9 will be EOL this October. I don't think we will do a new realease before...

[tfarago]

Doesn't psutil work only on linux? I get the motivation but the concrete cases you mentioned could be also handled without signals, or? Let's discuss this Friday in the meeting.

[MarcusZuber]

I did' t add psutil here... Sure, lets discuss it on Friday.