In the Python API, how can I redirect the output of an asynchronous function call of a function without return value?

I am using the Python API and I want to redirect the output of an asynchronously called function without return value. Is this maybe impossible?

My Python Script looks a little bit like this:

import matlab.engine as eng
import StringIO

out = StringIO.StringIO()

MAT = eng.start_matlab()
ret = MAT.func('arg', async=True, nargout=0, stdout=out)

while not ret.done() : pass

print out.getvalue()

MAT.quit()

When running this script, there is only a line feed / carriage return printed. The return value of

ret.result()

is "None".

Answer 1

[Bo Li]

What about adding "ret.result()" before printing the output buffer like following?

 while not ret.done() : pass
 ret.result()
 print out.getvalue()

[Sven-Eric Krüger]

It works. Thank you!

[Esteban Henriques]

From:

def result(self, timeout=None):

in fevalfuture.py, it seems that it is not possible to get any feedback from the out stream until the call is done. Doesn't this at least in part defeat the purpose of an async call?

[Sven-Eric Krüger]

@Esteban MATLAB itself is always single threaded, but you can asyncronuously call functions. So the Python Script will not hold on the call of the MATLAB Engine, but continue. The MATLAB Interpreter does his stuff on his own and so does the Python Interpreter.