[PyQt] PyQt Custom user types with QVariants and QMetaTypes

[Justin Rosen]

Hey all,

I've been struggling the past few days with trying to wrap my mind around
how PyQt has implemented QVariants and QMetaTypes.  In short I'm trying to
register/declare a custom user type that will be picked up by
QItemEditorFactory.

I've found a few postings related to the topic, but have been unable to get
a working example.  I'm using Qt 4.6.1 and PyQt 4.7.2 on Linux Red Hat
Enterprise 5.5

The FAQ clearly states that this is doable: "Can I store a python object
reference in a QVariant?"<http://article.gmane.org/gmane.comp.python.pyqt-pykde/11833>
And the original thread covering the issue in the FAQ: Construct QVariant
from object of user
type<http://old.nabble.com/Construct-QVariant-from-object-of-user-type-td16677823.html>
.

I'm able to store a python object on a QVariant and get the object back, For
example the following class Triplet:
>>> class Triplet:
...    def __init__(self):
...        self.first, self.second, self.third = (-1, -1, -1)

>>> t = Triplet()
>>> tv = QtCore.QVariant(t)
>>> assert tv.toPyObject() is t
True

But I can't seem to derive the type/userType as being a Triplet.  Comes back
as PyQt_PyObject and UserType:
>>> tv.type()
127
>>> tv.typeName()
'PyQt_PyObject'
>>> tv.typeToName(tv.type())
'UserType'
>>> tv.userType()
260
>>> tv.typeToName(tv.userType())
'PyQt_PyObject'

What am I doing wrong?  The FAQ says that new python types are automatically
registered, but I keep getting the same PyObject type.
"The QVariant() ctor will now register new Python types automatically. I've
also wrapped QMetaType.type() and overloaded it so that you can pass a
Python type. I think this is enough for what you need."

In a previous post Matt Newell posted some code that achieves this, but I'm
assuming this has been superseded by integration with sip?:
>>> class A: pass
>>> metaTypeId = registerPythonQMetaType(A)
>>> print metaTypeId
424
>>> qv = qvariantFromPyObject(A())
>>> qv
<PyQt4.QtCore.QVariant object at 0xb7d2ec2c>
>>> qv.userType()
424
>>> print qv.typeName()
A
>>> pyObjectFromQVariant(qv)
<__main__.A instance at 0xb65391ec>

Thanks, any help would be greatly appreciated!
Justin
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