[PyQt] Getting parent class for an enum

[J Barchan]

On 17 May 2018 at 11:18, Florian Bruhin <me at the-compiler.org> wrote:

> On Thu, May 17, 2018 at 11:14:18AM +0100, J Barchan wrote:
> > On 17 May 2018 at 10:12, Florian Bruhin <me at the-compiler.org> wrote:
> >
> > > On Thu, May 17, 2018 at 09:50:13AM +0100, J Barchan wrote:
> > > > ​I'm not sure whether ​I am hijacking a relevant thread, or whether
> this
> > > > can already be done, but I would like to know how to (easily) get the
> > > > symbolic string for an ItemDataRole constant:
> > > >
> > > > class MySqlQueryModel(QSqlQueryModel):
> > > >     def data(self, index: QtCore.QModelIndex, role:
> > > >
> > > ​​
> > > QtCore.Qt.ItemDataRole=QtCore.Qt.DisplayRole) -> typing.Any:
> > > >         print(role)
> > > >
> > > > ​How do I get to print that role as, say, "DisplayRole" instead of
> as 0,
> > > > for debugging?​
> > >
> > > I wrote something to do that here:
> > > https://github.com/qutebrowser/qutebrowser/blob/
> v1.3.0/qutebrowser/utils/
> > > debug.py#L96-L132
> > >
> > > Florian
> > >
> > > --
> > > https://www.qutebrowser.org | me at the-compiler.org (Mail/XMPP)
> > >    GPG: 916E B0C8 FD55 A072 | https://the-compiler.org/pubkey.asc
> > >          I love long mails! | https://email.is-not-s.ms/
> > >
> >
> > ​Dear Florian,
> >
> > Thanks!  Your qenum_key() looks promising *except for*:​
> >
> >
> >    1. I cannot find anything suitable to pass in as `base`, e.g.
> >
> >    qenum_key(QtCore.Qt, role,
> ​​
> klass=QtCore.Qt.ItemDataRole)
> >
> >    does not work.  I don't understand what it is I need here which has a
> >    base.staticMetaObject?
> >    2. Is this whole principle going to work for QtCore.Qt.ItemDataRole?
> So
> >    far as I can see, it's not some kind of enum in PyQt, it's just a
> class
> >    derived from int with a bunch of sundry member variables for various
> >    values.
>
> Seems to work fine for me:
>
>     >>> from qutebrowser.utils import debug
>     >>> from PyQt5.QtCore import Qt
>     >>> debug.qenum_key(Qt, Qt.DisplayRole)
>     'DisplayRole'
>
> (tried with PyQt 5.7.1 and 5.10)
>
> Florian
>
> --
> https://www.qutebrowser.org | me at the-compiler.org (Mail/XMPP)
>    GPG: 916E B0C8 FD55 A072 | https://the-compiler.org/pubkey.asc
>          I love long mails! | https://email.is-not-s.ms/
>

​My humble apologies!

I was confused in the PyCharm IDE, which highlights ​passing QtCore.Qt for
base with error message "Type '[Qt]' doesn't have expected attribute
'staticMetaObject'", and then stepping through qenum_key hit that

except AttributeError:

code path, and I thought it had gone wrong.  I now understand how your code
works, and that path is expected in my case!

For my case, I want to know the symbolic value in a role *variable*, which
has already been converted to an int.  That means I must pass qenum_key() a
​
klass=QtCore.Qt.ItemDataRole hint.  I now confirm my

qenum_key(QtCore.Qt, role, klass=QtCore.Qt.ItemDataRole)

is the correct formulation for me.

​I shall now ​add your qenum_key() & qflags_key() to my utility functions!
Thanks :)


-- 
Kindest,
Jonathan
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