[Development] Undeprecating QString::null

Uwe Rathmann Uwe.Rathmann at tigertal.de
Tue Jan 16 16:20:54 CET 2018

Hi all,

I received a bug report concerning a header of the Qwt library ( http://
qwt.sf.net ), that is using the deprecated QString::null.

Sure this is only a warning, but it is obviously something where Qwt 
users get irritated as they can't fix code of a 3rd party header.

The offending line looks like this:

    QwtText( const QString & = QString::null, ... );

So my first question would be, what is wrong about using QString:null and 
why using QString() is better. My second question then would be if this 
is also for Qt4 ( Qwt 6.1.2 supports all versions >= Qt 4.4 ) and older 
versions of C++ and compilers.

To be honest I don't want to create a new ( + binary incompatible ) 
version of Qwt and/or add even more version depending #ifdefs, as long as 
there is no good reason.


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