argos does not show output when failing to start

[bilderbuchi]

Hi!

This looks very awesome! I just tried installing argos, and seemingly succeeded, but running argos just didn't show anything. I went deeper and found that apparently your main function fails due to some PyQt5 problem, but afaict I followed your instructions, and have no idea how to fix it.

Console output (Windows 10 64bit, and Anaconda)

Microsoft Windows [Version 10.0.14393]
(c) 2016 Microsoft Corporation. Alle Rechte vorbehalten.

Z:\>conda create -n tryargos python numpy
Fetching package metadata .........
Solving package specifications: ..........

Package plan for installation in environment C:\Continuum\Anaconda3\envs\tryargos:

The following NEW packages will be INSTALLED:

    mkl:            2017.0.1-0
    numpy:          1.11.3-py36_0
    pip:            9.0.1-py36_1
    python:         3.6.0-0
    setuptools:     27.2.0-py36_1
    vs2015_runtime: 14.0.25123-0
    wheel:          0.29.0-py36_0

Proceed ([y]/n)?

Linking packages ...
[      COMPLETE      ]|##################################################| 100%
#
# To activate this environment, use:
# > activate tryargos
#
# To deactivate this environment, use:
# > deactivate tryargos
#
# * for power-users using bash, you must source
#

Z:\>activate tryargos

(tryargos) Z:\>pip install PyQt5 pyqtgraph argos
Collecting PyQt5
  Using cached PyQt5-5.7.1-5.7.1-cp34.cp35.cp36-none-win_amd64.whl
Collecting pyqtgraph
Collecting argos
Collecting sip>=4.19 (from PyQt5)
  Using cached sip-4.19-cp36-none-win_amd64.whl
Requirement already satisfied: numpy in c:\continuum\anaconda3\envs\tryargos\lib\site-packages (from pyqtgraph)
Installing collected packages: sip, PyQt5, pyqtgraph, argos
Successfully installed PyQt5-5.7.1 argos-0.2.1 pyqtgraph-0.10.0 sip-4.19

(tryargos) Z:\>argos -h

(tryargos) Z:\>argos

(tryargos) Z:\>python -m argos.main
Traceback (most recent call last):
  File "C:\Continuum\Anaconda3\envs\tryargos\lib\runpy.py", line 193, in _run_module_as_main
    "__main__", mod_spec)
  File "C:\Continuum\Anaconda3\envs\tryargos\lib\runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "C:\Continuum\Anaconda3\envs\tryargos\lib\site-packages\argos\main.py", line 200, in <module>
    main()
  File "C:\Continuum\Anaconda3\envs\tryargos\lib\site-packages\argos\main.py", line 186, in main
    from argos.qt.misc import ABOUT_QT_BINDINGS
  File "C:\Continuum\Anaconda3\envs\tryargos\lib\site-packages\argos\qt\__init__.py", line 23, in <module>
    from argos.qt.misc import Qt, QtCore, QtGui, QtWidgets, QtSvg, QtSignal, QtSlot
  File "C:\Continuum\Anaconda3\envs\tryargos\lib\site-packages\argos\qt\misc.py", line 83, in <module>
    from PyQt5 import QtCore, QtGui, QtWidgets, QtSvg
ImportError: DLL load failed: Das angegebene Modul wurde nicht gefunden.

(tryargos) Z:\>

(The german bit says "the specified module could not be found")

Any ideas what's wrong here? Also, I would have expected that argos does not silently swallow the encountered exception, and would at least log something I can see to even know that something went wrong.

[titusjan]

It seems that there is a problem with your PyQt5 installation. Let's try to confirm this by bypassing Argos and importing PyQt5 directly from Python. Can you try the following command from the shell?

c:\> python -c "from PyQt5 import QtCore, QtGui, QtWidgets, QtSvg"

If you get the same error we are sure that PyQt5 is the culprit.

I noticed that you installed PyQt5 with pip, even though you have anaconda. You could perhaps uninstall from pip and then use conda install pyqt to install PyQt again. I know PyQt 5.7 is not yet available on Anaconda, but 5.6 works fine with Argos.

Also, I would have expected that argos does not silently swallow the encountered exception, and would at least log something I can see to even know that something went wrong.

The Argos installer creates some platform-specific scripts or programs (e.g. the argos.exe) to abstract away some OS differences (see https://setuptools.readthedocs.io/en/latest/setuptools.html#automatic-script-creation). Unfortunately these scripts swallow the exceptions.

I ran into the same problem, that's why I wrote the trouble shooting section, which you've found. I agree with you that this is undesirable but I don't know how to configures the setup_tools package to create scripts that don't swallow the exceptions. If anybody knows this, please tell me.

[bilderbuchi]

If you get the same error we are sure that PyQt5 is the culprit.

Yes, in the meantime I have confirmed that from PyQt5 import QTCore is the minimum failing example.

use conda install pyqt

Ha, I overlooked that! I had some fears about pyqt4/5 coexistence problems (and need pyqt4 still for matplotlib and friends), so I made a separate environment. Didn't realize I could as well install pyqt that way. Interestingly, conda's pyqtgraph version is currently not new enough, and demands pyqt4 still, so I installed that via pip.

Anyway, it starts now, thank you! Now to wait until the rest of the scientific python ecosystem moves to pyqt5, so I don't need a separate environment. :D

[bilderbuchi]

Regarding your point about the exceptions, in your argos.main.main() you could catch all exceptions (maybe except systemexit et al) and log them to stdout/err using logging.Logger.exception().

[titusjan]

The problem is that argos.exefails before argos.main.main() is even called.