From the mailing list:

QWidget().style().standardIcon() call fails with PySide, but works if
result of each call in a chain is assigned to a variable.

---[code]
from PySide.QtGui import QApplication, QWidget, QStyle

app = QApplication([])

q = QWidget()
s = q.style()
print s.standardIcon(QStyle.SP_TitleBarMinButton)

s = QWidget().style()
print s.standardIcon(QStyle.SP_TitleBarMinButton)
---[/code]

---[output]
<PySide.QtGui.QIcon object at 0x02BB7A00>
Traceback (most recent call last):
  File "testmy2.py", line 10, in <module>
    print s.standardIcon(QStyle.SP_TitleBarMinButton)
RuntimeError: Internal C++ object already deleted.
---[/output]

--------------------------------
and:

We have the following

class QReduceBlockData(QTextBlockUserData):

    def __init__(self,n):
        QTextBlockUserData.__init__(self)
        self.message = "Hallo " + str(n)

Somewhere else in our code, we try:

cursor.block().setUserData(QReduceBlockData(4711))
print cursor.block().userData().message

This yields an error: "RuntimeError: Internal C++ object already deleted."

If we introduce a variable like

data = QReduceBlockData(4711)
cursor.block().setUserData(data)
print cursor.block().userData().message

Then it works.