Transitive const sucks

[Bruce Adams]

Carsten Sørensen Wrote:

> Alex Burton wrote:
> > While const is being reexamined....
> > 
> > I create an interface :
> > 
> > interface Server
> > {
> >     Data getData() const;
> > };
> 
> Hello, world! I'm fairly new to the world of D, but a minor detail like 
> that has never stopped me from butting in so far ;) I'm sorry if any of 
> my points have been made before, but I don't really feel like trawling 
> through all 50.000 posts (although I have made an effort to dig into the 
> more recent ones)
> 
> First of all, I think specifying an interface method to be const is bad 
> practice. The interface is assuming things about a possible 
> implementation that is really not its business. As you describe, this 
> will hinder your implementation.
> 
> I understand you're not able to specify your particular getData() 
> implementation as const due to const's transitivity, but as far as I'm 
> concerned them's the breaks. I'm a bit of a const purist, sorry.
> 
> What I would like to see regarding const and interfaces, is that the 
> _implementation_ should be able to guarantee const-correctness even if 
> the interface doesn't, much like covariant return types. The 
> implementation should be free to guarantee more than its interface. That 
> doesn't help you though...
> 
> 
> Best regards,
> Carsten Sørensen

Someone correct me if I'm wrong but I thought D doesn't / wasn't going to support overloading methods on whether they are const or not. So this part of the discussion is almost moot.

Bruce.