any news on const/invariant?

[Sean Kelly]

Walter Bright wrote:
> Derek Parnell wrote:
>> If this truely is a case where "Head const turned out to be an
>> unexplainable, incomprehensible feature." and/or is too hard to 
>> implement,
>> then I'll go with the flow. I haven't seen evidence of that being the 
>> case
>> yet, regardless of Walter's statements so far.
> 
> The only person I know of who understood it was Andrei. This is despite 
> many hours spent trying to explain it with pencil and paper, on 
> whiteboards (at the D conference), and on the n.g. Now, I'll be the 
> first to say I stink at explaining concepts to people, but I watched 
> Andrei try and fail at this repeatedly, and Andrei is very good at 
> explaining things.
> 
> I do not know why it is so hard to explain, but it is, and it's clear I 
> was bashing my head on a rock with it, and that rock was going to sink D 
> 2.0 if it wasn't changed.

My issue with the design wasn't so much with the conceptual complexity 
(though this was still a bit high) as with the complexity it promised to 
add to code.  The const features in C++ are simpler from a semantic 
standpoint than the proposed const features in D, and yet they can 
complicate code tremendously.  With D I would prefer to sacrifice a bit 
of functionality in exchange for simpler code.


Sean