Send SigTo() object to child process

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Alexandros

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Sep 21, 2021, 8:39:14 AM9/21/21
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I want to call a child process that will set values to a couple of
SigTo() objects. I've seen the examples in Pyo's documentation with the
SharedTable() approach, but I was wandering if it's possible to do
something like the following:

```
''' Script called subproc_script that will be loaded in a terminal
session'''

import multiprocessing as mp

def subproc(siglist):
    lst = [0, 0]
    # do some processing here
    for i in range(2):
        siglist[i].setValue(lst[i])

def parentproc(siglist):
    p = mp.Process(target=subproc, args=(siglist,))
    p.start()
```

The above code should be imported in a terminal session and called this way

```
import subproc_script as sub

sigs = [SigTo(0) for i in range(2)]
sub.parentproc(sigs)
```

Of course this doesn't work. There is no error produced, but the values
of the SigTo() objects do now change in the terminal.

Any ideas?

Alexandros Drymonitis

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Sep 22, 2021, 7:26:27 AM9/22/21
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Here's another attempt, following the multiprocessing example of sharing audio signals. This script is called gmaps.py:
```
import multiprocessing as mp
import googlemaps
from countryinfo import CountryInfo
import pycountry
from random import randrange
from pyo import *

class LatLng(mp.Process):
       def __init__(self, buf_size):
               super(LatLng, self).__init__()
               self._bufsize = buf_size

       def run(self):
               self.server = Server()
               self.server.setInOutDevice(2)
               self.server.boot()
               self.server.start()

               self._writetab = SharedTable(["/lat", "/lng"], True, self._bufsize)
               self._sigs = Sig([0, 0])

               self._capital = None
               self._gmaps = googlemaps.Client(key=key)
               self._num_countries = len(pycountry.countries)

       def getloc(self):
               while self._capital is None:
                       try:
                               self._capital = CountryInfo(list(pycountry.countries)[randrange(self._num_countries)].name).capital()
                       # some countries produce key errors
                       except KeyError:
                               pass
               geocode_result = self._gmaps.geocode(self._capital)
               lat_lng = [abs(geocode_result[0]['geometry']['location']['lat']), abs(geocode_result[0]['geometry']['location']['lng'])]
               self._capital = None
               self._sigs.setValue(lat_lng)
               rec = TableFill(self._writesigs, self._writetab)

```

This has to run inside Pure Data with the [pyo~] external. The idea is that the main script loaded in [pyo~] is the following:
```
import gmaps as gm
loc = gm.LatLng(_s_.getBufferSize())
loc.start()
t = SharedTable(["/lat", "/lng"], False, _s_.getBufferSize())
l = TableScan(t)
loc.getloc()
```
The thing is that the last line produces a "bad code" error. When I try to import the gmaps.py script in a terminal, a get an error on `loc.start()` saying that the server has not been started. In Pd though, I don't get an error there, but only when I call `loc.getloc()`. Since Pd doens't output enough information on errors, but only the "bad code" message, and since in the terminal I get an error earlier than that, it's hard to trace what is going on. Can someone help me?

Alexandros Drymonitis

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Sep 29, 2021, 2:09:52 AM9/29/21
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Eventually, I went with OSC, so the child process is launched and sends its values with OSC to a OscDataReceive() object, which calls a function to update the values of the two SigTo() objects. Worked fine, so I won't bother any longer with the code above.
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