Using nullptr instead of Q_NULLPTR

Thiago Macieira thiago at
Fri Aug 14 21:28:49 BST 2015

On Friday 14 August 2015 04:07:41 Thomas L├╝bking wrote:
> We could just detect the compiler, and in need define nullptr 0x0, look the
> other side and hope for the best (ie. anybody on modern compilers anyway
> and nobody actually making use of std::nullptr_t atm. but just of the
> keyword) - not very nice, but better than breaking compilation(?) and not
> as invasive.

It's not the same thing.

First of all, it can't be a variable, it would have to be a macro. Second, a 
literal zero can be cast to boolean, integrals and floating point, but nullptr 
can't. That's the whole reason why nullptr exists in the first place.

Q_NULLPTR isn't nullptr: when you use it, you acknowledge that it may be a 
zero and thus won't resolve ambiguities when calling overloads -- or, worse, 
will call the wrong overload (the one with int instead of the one with a 

Defining a macro for nullptr is dangerous...

My recommendation: it's broken now so leave it. Fix it if someone complains, 
but otherwise just leave it. In one year's time, the discussion will be moot.

Thiago Macieira - thiago (AT) - thiago (AT)
   Software Architect - Intel Open Source Technology Center
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