On 9/23/2011 7:09 PM, Jonathan M Davis wrote:
Then the lack of logical const is really your issue, not the
transivity. Granted, logical const would be less of an issue if const
weren't transitive, but ultimately, it's the fact that there is no way
to alter a const variable without subverting the type system that's
your problem.
Yeah, so we both seem to agree that the *cause* of the problem
(inability to have logical const, or whatever you want to call it, I
don't really care what it's called) is the presence of transitive const.
I'm not talking about the problem, but the cause.
If you don't care about purity, it _is_ possible to have caching and
lazy loading, but it's a bit ugly IMHO.
Yeah, that's why I think we should remove the transitivity. Then this
would be a non-issue.
...
No idea what you were saying since I don't know what "AA" stands for,
sorry. :(
So, is the fact that D's const does not allow for any kind of caching
or lazy loading the only issue that you're really seeing with const
(beyond implementation issues)?
Actually, it IS an implementation issue, not a performance/optimization
issue.
i.e. this class reads from a terminal, and it's not like I can make it
read at a different time, since doing so at the wrong time would cause
it to deadlock. So I have to grab the input on the first fetch, and it's
not like I'm doing this to optimize anything... the code simply _won't
function_ if I don't do this.
It _is_ an issue, and the transivity does make it worse, since more
stuff is const than would be otherwise, but are there other issues
beyond that?
See above. It's a real issue, not a performance issue.
I think that it would be great if we could find a solution to lazy
loading and caching so that it works with const, but I fear that at
this point, that that is relegated to D3 unless someone can come up
with a very clever solution that is backwards compatible.
I guess that means D might not really catch on until D3? Problems like
this come up often enough to make D kind of annoying to use...
