replace pyqt4 with pyqt

[jayich]

qtpy gives us great flexibility. It works with qt4 or qt5. qt4 is at the point now where it is nontrivial to install in some cases (probably most).

[gregllong]

I think Andrew means qtpy

[jayich]

yes, corrected.

[aransfor]

according to https://github.com/spyder-ide/qtpy you still need to install qt4 and or qt5 so this does not help with the problem

[jayich]

The point here is that you can install qt4 or qt5 and the code will still work.

[aransfor]

I guess personally I would rather just switch to 5 eventually than have some intermediary thing

[gregllong]

The idea here is that since for our python 2.7 applications the Qt package that goes with the system is PyQt4, and for python 3.5 it's PyQt5 (I think this is true), it feels like backward compatibility is going to be necessary

[jayich]

Reading into pyqt I think we should at least switch to pyqt as an intermediate step before switching to pyqt5, if that is even desirable. pyqt5 has API changes from pyqt4, annoying. What is the argument for not using pyqt and letting the end user decide when/if they switch to pyqt5? or later likely pyqt6.

In any case, again I think it is better to incrementally move to pyqt5 through qtpy. Then when everyone is running pyqt5 we can discussing switching from qtpy to pyqt5. No one will notice the change from pyqt4 to qtpy except for running pip once. Not true for switching to pyqt5.

[aransfor]

I would prefer not to refactor the code twice.

[jayich]

The nice thing here is that you don't have to. @gregllong or I can knock this out.

[aransfor]

perhaps. I for see still having to test all the code I use to make sure it works and correcting things as they come up. This is always more time consuming than it seems

[jayich]

reading more carefully (here: https://pypi.python.org/pypi/QtPy) going to qtpy and then pyqt5 (if desirable) is the way to go. The switch from qtpy to pyqt5 is a replace all of qtpy with pyqt5.

I don't know how to lock step everyone upgrading their respective code bases to pyqt5. If we move to qtpy people can upgrade to pyqt5 whenever is convenient for their experiment.

[jayich]

A related issue: qt4reactor vs. qt5reactor. We should be able to do something like

try: 
    import qt4reactor as reactor
else: 
    import qt5reactor as reactor

[jayich]

For qt5reactor viability and easy pip installation it seems we are waiting on this PR.

Give the final comment a thumbs up.

[aransfor]

I mean I stand by what I said before that I think this has no clear benefit but will require everyone digging through there code... From my experience with "simple changes" to script scanner and the camera for instance it affected our experimental ability with only subjective organizational gains. That's my opinion FWIW

[aransfor]

Perhaps the real way to handle this stuff is to have a fork for refactoring changes like this and if you want to use that fork you can, plus those forks can merge periodically from common

[jayich]

@aransfor , I will look into qtpy and see if this is viable on a branch or fork.

[crwood]

For qt5reactor viability and easy pip installation it seems we are waiting on this PR.

Give the final comment a thumbs up.

I have recently taken over maintainership of the qt5reactor library and have since cut a new release (0.4) with the PR in question merged. I hope this will help ease your transition to Qt5!

[jayich]

@crwood thank you!

[crwood]

No problem! Please let me know if you come across any other outstanding issues along the way.

[jayich]

Anaconda no longer supports pyqt4. Would be great to have code that works with pyqt4 or pyqt5.

[gregllong]

A potential way of allowing for both pyqt4 and pyqt5 could be this. This requires the use of pyqtgraph which is not a problem for us

[jayich]

I'm not sure if we can do this, but if we can import the try/except statement so that we don't repeat that code switching between this method and potentially just pyqt4 or pyqt5 would be much easier. Not repeating this code should be possible.

[aransfor]

I vote for just switching to PyQt5 if were gonna do it then just get it done

[jchristensen133]

I like the idea of switching to pyqt5. If the changes to the existing code are minimal, then I agree with @ransford. Can you guys comment on how much you think the existing code will need to be changed?

On Tue, Sep 12, 2017 at 10:59 AM, Anthony Ransford <notifications@github.com

wrote:

I vote for just switching to PyQt5 if were gonna do it then just get it done

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[aransfor]

I just want to iterate that we should not maintain support for anaconda since this is just some specific package manager. However I think upgrading to pyqt5 is valuable in its own right and we should start a linger term branch that implements pyqt5

[jayich]

Regarding the amount of changes to existing code this is best figured out in a branch. The one big difficulty in switching to pyqt5 is changing other dependent repositories when common is ready. Just a number of moving pieces.

[aransfor]

@theoriginaljuice from looking at the pyqt5/pyqt4 differences there is a change to the signal and slots in pyqt5 as well as some changes to the Qdialog stuff. It looks like the former is used in scriptscanner quite a bit so it would have to be ported while as far as I know @gregllong is the only one who uses Qdialog so he can comment on how hard that change will be.

see here for differences http://pyqt.sourceforge.net/Docs/PyQt5/pyqt4_differences.html

[aransfor]

I agree with @jayich with other repos as well as scripscanner being the biggest issues, again without a branch (and a volunteer) we wont really know

[jayich]

Outside of Qdialog does getting scriptscanner working with pyqt5 cover all known pyqt usage? Getting scriptscanner working with pyqt5, test (on branch) and then implement the other pyqt5 changes through common might be an efficient route forward.

[aransfor]

I agree