References in D

[Jonathan M Davis]

On Saturday, September 15, 2012 19:57:03 Henning Pohl wrote:
> On Saturday, 15 September 2012 at 17:12:23 UTC, Jonathan M Davis
> 
> wrote:
> > Of course people use it. Having nullable types is _highly_
> > useful. It would
> > suck if references were non-nullable. That would be _horrible_
> > IMHO. Having a
> > means to have non-nullable references for cases where that
> > makes sense isn't
> > necessarily a bad thing, but null is a very useful construct,
> > and I'd _hate_
> > to see normal class references be non-nullable.
> > 
> > - Jonathan M Davis
> 
> And many usages of null as a state leads to really bad design.
> There are functions which behaviour is completly different if you
> pass null instead of a valid pointer/reference. An example would
> be:
> 
> http://www.khronos.org/registry/cl/sdk/1.1/docs/man/xhtml/clGetDeviceIDs.htm
> l

I'd argue that using null for indicating something other than the lack of a 
value is bad design. But there are plenty of cases where being able to 
indicate that there is no value is useful. And if a function requires that a 
pointer or reference or array or whatever have a value, then there's always 
DbC or exceptions. Just because someone can misuse a feature doesn't mean that 
a feature shouldn't be there.

- Jonathan M Davis