import qtpy raise except when only have PyQt4

[DengZuoheng]

qtpy/qtpy/__init__.py

Line 197 in 61e8432

from . import QtDataVisualization as QtDatavisualization

>>> import qtpy
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/python3.8/site-packages/qtpy/__init__.py", line 237, in <module>
    from . import QtDataVisualization as QtDatavisualization
  File "/python3.8/site-packages/qtpy/QtDataVisualization.py", line 22, in <module>
    raise PythonQtError('No Qt bindings could be found')

Why you remove the QT_API check before import QtDataVisualization since 1.11.2?

[dalthviz]

Hi @DengZuoheng thank you for the feedback! Regarding this issue, we added the lines causing it in order to keep compatibility since previously to import QtDataVisualization we were using QtDatavisualization instead of QtDataVisualization (note the lower case v). Before this aliasing was done I suspect this error could happen only if you directly runned something like from qtpy import QtDatavisualization while using Qt4 (either PySide or PyQt4).

Anyhow, hope the info above clarifies a little bit the situation :)

[dalthviz]

Also @DengZuoheng , just out of curiosity, you keep using Qt4 in your current projects?

[DengZuoheng]

@dalthviz thanks for your prompt reply. And yes, we still using Qt4 now, and we going to upgrade to Qt5 next year. Before that we trying to upgrade qtconsole, and meet this issue.

[CAM-Gerlach]

@dalthviz I assume we'll drop support in QtConsole at some point soon, if we haven't already done so?

Also, just FYI @DengZuoheng , QtPy 1.12 (presumably the last minor release of the 1.x series) will formally deprecate the Qt4 bindings (which have been mostly untested since QtPy 1.9.x) and QtPy 2.0 will no longer support Qt <5.6 for sure, maybe Qt <5.9 (since we can't easily test on versions lower than that and they are long-EoL upstream) and possibly even Qt <5.12, to allow for new functionality, cleaner code and higher performance with less maintenance overhead.

[dalthviz]

@dalthviz thanks for your prompt reply. And yes, we still using Qt4 now, and we going to upgrade to Qt5 next year. Before that we trying to upgrade qtconsole, and meet this issue.

Thanks @DengZuoheng for the answer, glad to know that you are already checking a migration plan 👍

@dalthviz I assume we'll drop support in QtConsole at some point soon, if we haven't already done so?

I think that depends on QtConsole adding a constrain in QtPy but maybe @ccordoba12 knows better

[ccordoba12]

we'll drop support in QtConsole at some point soon, if we haven't already done so?

I doubt Qtconsole can still work with PyQt4 because it only supports Python 3.6+ (and I think there are no PyQt4 packages for that version).