Vision for the D language - stabilizing complexity?

[Andrew Godfrey via Digitalmars-d]

On Friday, 15 July 2016 at 11:09:24 UTC, Patrick Schluter wrote:
> On Friday, 15 July 2016 at 10:25:16 UTC, Shachar Shemesh wrote:
>>
>> I think the one that hurts the most is fixing "C++ fault" #3. 
>> It means there are many scenarios in which I could put const 
>> in C++, and I simply can't in D, because something somewhere 
>> needs to be mutable.
>
> Then it is not const and marking it as const is a bug. D 
> enforces to not write a bug, what's wrong with that?

One example is if you make a class that has an internal cache of 
something. Updating or invalidating that cache has no logical 
effect on the externally-observable state of the class. So you 
should be able to modify the cache even on a 'const' object. This 
is not a bug and I've seen it have a huge effect on performance - 
probably a lot more than the const optimizations Walter is 
talking about here.