Reading your example I check you connect a string slot to a double signal. In
my point of view this is not correct, but I do not know if this is valid in a
QML program.

I changed you example creating a new slot with float signature and connect this
signal 'textRotationChanged' to this new slot and everything works fine.

Now I need to now if is valid connect a string slot with a double signal, if
this is valid then we have a bug on PySide.

I created a similar test on cpp, and this behavior is the same as python, 

After some investigation I discovered the problem. QML was emitting a wrong
singal when calling the 'output' method with QString signature. 

For some reason QML aways call the double signature.

This only happen when you have 2 slots with the same name but different
signatures in the same object.


Then we can conclude with this examples, this is a QML bug.

Check my example, if you agree with me, please close the bug, and fell free to
report this on Qt bugzilla.

Created attachment 135 [details]
cpp example

Thanks for the C++ sample. An interesting thing there is that if I switch the
order in which the slots are declared (in the header file), the C++ example
works.

However, the behaviour is slightly different in Python. If I leave
textRotationChanged disconnected and then add the following slot decoration:

    @QtCore.Slot(str)
    @QtCore.Slot(float)
    def output(self,s):
    print s

the example still works as before (I believe the slots are declared in inverse
order of the decorators because of their "recursive" behaviour). However, if I
switch the order of the decorators:

    @QtCore.Slot(float)
    @QtCore.Slot(str)
    def output(self,s):
    print s

then I get:

123.0
nan

I guess this is fine and consistent with the C++ example. However, even if I
have added the explicit float decorator and then connect textRotationChanged,
the thing still breaks! Is this a separate issue?

As discussed on the IRC: when connecting textRotationChanged in Python, an
implicit slot with 'double' signature is added. If the explicit signature is
made 'double', everything works again.

Another part of the issue is that QML always picks the first overloaded slot in
Qt meta object. This is a bug in QML and will be fixed in Qt 4.7.2:

http://bugreports.qt.nokia.com/browse/QTBUG-11604?page=com.atlassian.jira.plugin.system.issuetabpanels%3Aall-tabpanel

Since there doesn't appear to be any PySide issue behind this, I'm resolving
the bug as invalid.

Released on version 1.0.0~beta1