Thanks for the report.

The problem here is the instance type was printed wrong, the correct type for
instance signals is "SignalInstance", this is necessary due some "magical"
stuff which is need to have Qt signal working on python.

I have fixed that, and created a new unit test base on this one, you can check
that on : https://github.com/PySide/PySide/blob/master/tests/QtCore/bug_931.py

the fix can be found on the pyside commit:

commit 58e3040802eedae58e9dd6443c2a59ebaa97f888
Author: Renato Filho <renato.filho@openbossa.org>
Date:   Mon Jul 18 15:18:06 2011 -0300

Is not more elegant to override the `__instancecheck__()` method?

For example:

    def __instancecheck__(self, instance):
        return (type(instance) == Signal)

Or maybe more complete:

    def __instancecheck__(cls, instance):
        mro = getattr(instance, '__mro__', None)
        if mro:
            return (Signal in mro)
        else:
            return (type(instance) == Signal)

Overriding this method, is easy to check whether a instance attribute is a
signal, just type the following:

    isinstance(o.destroyed, Signal)

Instead:

    type(o.destroyed).__name__ == "SignalInstance"

I think this way is more elegant and pythonic, you can implement it?

Sorry, my `__instancecheck__()` implementations are wrong. The following is
better:

class SignalType(type):

    def __instancecheck__(cls, instance):
        mro = getattr(instance, '__mro__', None)
        if mro:
            return ((Signal in mro) or (SignalInstance in mro))
        else:
            return (type(instance) in (Signal, SignalInstance))

class Signal:
    __metaclass__ = SignalType

sure this is a best idea i will check how to implement this on c python,
thanks.

update in pyside commit:

commit 017fbee08f78a0dcab8c26b9da23f889752dce70
Author: Renato Filho <renato.filho@openbossa.org>
Date:   Mon Jul 25 18:37:22 2011 -0300

Released on PySide 1.0.6