Proxy() raises exception when starting server in Rhino Mac 6

Describe the bug

While launching a Proxy() server in rhino mac 6.0, a ValueError exception is raised by rhino’s subprocess.py stating: “Cannot redirect stderr to stdout yet.”.

Having a closer look at it, this issue arises when instantiating Popen()in proxy’s start_server() method as the system complains about the arguments being passed to the stdout and stderr parameters of the constructor. In its current state, it looks as follows:

self._process = Popen(args, stdout=PIPE, stderr=STDOUT, *args, **kwargs)

Went to check whether the issue would persist should an XFunc() would be called, and to discard if this was a shady rhino-for-mac-update-issue, but to my surprise this operated fine.

Therefore, after inspecting what is dissimilar between Proxy() and XFunc(), I have got around the problem by setting stderr equal to PIPE; looking in sum as follows:

self._process = Popen(args, stdout=PIPE, stderr=PIPE, *args, **kwargs)

Nevertheless, I am not sure if this modification would have any potential side effects down the road.

To Reproduce

from compas.rpc import Proxy
from compas.utilities import XFunc

my_xfunc = XFunc('myfavoriteexternalmethod')
print('xfunc worked like a charm')

my_proxy = Proxy()
print('proxy worked like a charm too')

Expected behavior Proxy() server should be started smoothly.

Desktop:

• OS: OSX Mojave
• Python version: IronPython 2.7.5 in Rhino Mac 6.0
• Python package manager. Anaconda

[yijiangh]

Just for documentation purposes, this PR (“by coincident”) fixed the Exception: Fault error message when users are trying to use RPC and Proxy with VRay for Rhino installed on their computer. I tested it on my Windows 10 laptop, python 3.7, VRay for Rhino 4.00.02.

This bug was reported when using RPC and Proxy in compas 0.7.2 in a workshop with @stefanaparascho.

[arpastrana]

Closed after PR was merged to master.