[PyKDE] QString -> python string via QString::latin1()

[Nigel Stewart]

Hello all,

I came across something unexpected recently,
that was causing us occasional python
exceptions:

 >> print type(qt.QString("foo").latin1())
<type 'str'>
 >> print type(qt.QString("").latin1())
<type 'str'>
 >> print type(qt.QString.null.latin1())
<type 'NoneType'>
 >> print type(qt.QString().latin1())
<type 'NoneType'>

The type of result returned by the PyQt
binding for QString::latin1() depends
on whether the string is empty or null.

Contrast this with the PyQt binding for
the str() converter:

 >> print type(str(qt.QString("foo")))
<type 'str'>
 >> print type(str(qt.QString("")))
<type 'str'>
 >> print type(str(qt.QString.null))
<type 'str'>
 >> print type(str(qt.QString()))
<type 'str'>

In this case, conversion to a python
string always succeeds, and never
results in a NoneType.  PyQt is checking
for the QString::null in this case,
but for latin1() is defaulting to
the behaviour of PyString_FromString:

PyObject *PyString_FromString(const char *v)
   Return value: New reference.
   Returns a new string object with the value v
   on success, and NULL on failure. The parameter
   v must not be NULL; it will not be checked.

Overall, a bug, or a feature?  I would certainly
prefer that PyQt always returned a python string,
treating QString::isNull() and QString::isEmpty()
as the same case.  I'm interested in the broader
PyKde/PyQt opinion, is it "pythonic" to return
different types of objects, depending on the
input?

I'm using Python 2.4, Sip 4.1.1 and PyQt 3.13.

Regards,

Nigel Stewart