[Qt-interest] QLabel text () returns QString::null aftersetting empty QString

[Frank Hemer]

On Thursday 09 September 2010 19:23:43 Scott Aron Bloom wrote:
> -----Original Message-----
> From: qt-interest-bounces at trolltech.com
> [mailto:qt-interest-bounces at trolltech.com] On Behalf Of Frank Hemer Sent:
> Thursday, September 09, 2010 10:19 AM
> To: qt-interest at trolltech.com
> Subject: Re: [Qt-interest] QLabel text () returns QString::null
> aftersetting empty QString
>
> On Thursday 09 September 2010 19:07:25 Thiago Macieira wrote:
> > Em Quinta-feira 09 Setembro 2010, às 15:38:33, Frank Hemer escreveu:
> > > Is the behavior mentioned in the subject intended/known or is it a bug
> > > that needs to be filed?
> >
> > Unless otherwise specified in the documentation, you shouldn't rely on
> > methods keeping the null-vs-empty setting.
>
> Thanx for clearing this.
>
> However this makes it impossible to track if objects (QLabel, QLineEdit,
> QTextEdit and probably others) have been modified bec. comparing former
> state to later state is no more possible:-( ... for code that
> differentiates between QString ("") and QString::null ...
>
> Frank
> ------------------------------
>
> Not unless you simply tag it when you watch for the textChanged signals..
> Though for QLabel, the user cant modify the label directlky so Im not sure
> how it would be so difficult to track.
>
> Scott

Well ... thats just the point: QLabel is not a real problem here as it can be 
worked around by adding tracking code ... but what about the other QWidget 
derived classes that return QString? Using textChanged is of no use here 
since it already hides the possible 'null' string.

I'm using this in a scripting environment - the only way would be to derive 
from the base class and overwrite _ALL_ methods that somehow modify the 
contained string ... I'm sure it is way easier to fix the class itself to 
return what it  was set to before ...

Frank