[PyKDE] Printing empty QStrings

[Phil Thompson]

Johannes Sixt wrote:
> 
> On Wed, 01 Nov 2000, you wrote:
> >Boudewijn Rempt wrote:
> >> >>> print (QString())
> >> None
> >> >>> print (QString(""))
> >>
> >> >>> print (QString("a"))
> >> a
> >>
> >> instead of:
> >>
> >> >>> print (QString())
> >>
> >> Traceback (most recent call last):
> >>   File "<stdin>", line 1, in ?
> >>   File "/usr/local/lib/python2.0/site-packages/qt.py", line 898, in
> >> __str__
> >>     return str(self.sipThis)
> >> TypeError: __str__ returned non-string (type None)
> >
> >This is sensible, but can't be achieved. It is Python raising the
> >exception (not PyQt) because PyQt is returning the None object instead
> >of a string object. PyQt could return a string object containing "None"
> >(although "null" would be better) but then 'print QString()' and 'print
> >QString("None")' would do exactly the same thing.
> 
> IMHO, it is an error to distinguish between an "empty" string and a "null"
> string. In a program you usually want that they behave identical
> (concatenation, searching, replacing, etc...), they should even compare equal
> (if you have 2 string variables, a and b, one contains the empty string, the
> other contains the null string, then you want that a==b is true in almost any
> case!).
> 
> So, why make a difference at all?
> <algebra>
> My suggestion: treat them both like the neutral element of the monoid of
> strings and the concatenation operation, i.e. the so-called emtpy string.
> </algebra>

What does Qt do? What gives the fewest surprises to a C++ Qt programmer
coming to PyQt?

Phil