PyQt4 4.11.4 no longer accepts QBrush(None) or QColor(None)

Question

With PyQt4, I had always been able to initialize QBrush and QColor with None as argument (creates no color etc):

QBrush(None)
QColor(None)

But after I upgraded from 4.11.3 to 4.11.4 (which is a minor upgrade), I found these are no longer accepted:

>>> QColor(None)
Traceback (most recent call last):
  File "<console>", line 1, in <module>
TypeError: arguments did not match any overloaded call:
  QColor(Qt.GlobalColor): argument 1 has unexpected type 'NoneType'
  QColor(int): too many arguments
  QColor(QVariant): argument 1 has unexpected type 'NoneType'
  QColor(): argument 1 has unexpected type 'NoneType'
  QColor(int, int, int, int alpha=255): argument 1 has unexpected type 'NoneType'

I have tried to search on the changes between 4.11.3 and 4.11.4 but cannot see any relevant information that explains this. And I started to wonder if I am searching the right thing.

Is this caused by the changes in Qt? or PyQt4? or python-SIP?

Also I don't actually understand what the underlying (C++) call in Qt is. Is it actually calling QBrush() and QColor() or is it trying to change Python None to c null?

Thanks, I hope I didn't miss something obvious online.

"the None value can be specified wherever NULL is acceptable to the underlying C++ code" ([PyQt Doc](http://pyqt.sourceforge.net/Docs/PyQt4/gotchas.html#none-and-null)). But I have no idea why `QBrush(None)` was valid before and not now. — Mel, Oct 07 '15 at 13:13

ekhumoro · Accepted Answer · 2015-10-07T16:28:45.463

The PyQt-4.11.4 ChangeLog has this entry:

2015-02-06 Phil Thompson

PyQt4.msp: Fixed all pseudo-ctors that take a QVariant argument. [5c941d8fb16b] <4.11-maint>

And here's the relevant parts of the diff for sip/QtGui/qcolor.sip:

--- PyQt-x11-gpl-4.11.3/sip/QtGui/qcolor.sip    2014-11-09
+++ PyQt-x11-gpl-4.11.4/sip/QtGui/qcolor.sip    2015-06-11
@@ -75,13 +70,17 @@

     QColor(Qt::GlobalColor color /Constrained/);
     QColor(QRgb rgb);
-    QColor(const QVariant &variant) /NoDerived/;
+    QColor(const QVariant &variant /GetWrapper/) /NoDerived/;
 %MethodCode
         #if QT_VERSION >= 0x050000
-        sipCpp = new QColor(a0->value<QColor>());
+        if (a0->canConvert<QColor>())
+            sipCpp = new QColor(a0->value<QColor>());
         #else
-        sipCpp = new QColor(qVariantValue<QColor>(*a0));
+        if (qVariantCanConvert<QColor>(*a0))
+            sipCpp = new QColor(qVariantValue<QColor>(*a0));
         #endif
+        else
+            sipError = sipBadCallableArg(0, a0Wrapper);
 %End

     QString name() const;

So it seems that the copy constructors now check whether QVariant can convert the argument to a QColor/QBrush, and if not, an error is raised.

PyQt4 4.11.4 no longer accepts QBrush(None) or QColor(None)

1 Answers1