On 9/23/2011 3:56 PM, Jonathan M Davis wrote:
The complaints have generally been about the lack of logical const and
the inability to cast away const and modify variables _not_ about
transitiveness. I'm not say that there have been _no_ complaints about
the transitiveness about const, but I can't recall even _one_ issue
with it at the moment. It's the lack of logical const that's generally
complained about and has shown itself to be a major blocker for const
in some cases. - Jonathan M Davis
But the only reason logical const is an issue is indeed the fact that
const is transitive.
To illustrate, I run into problem almost every other time I use D, and
to me it's *only* a problem because source is const:
class MyRange : InputRange!char
{
char peeked;
InputRange!char source;
char front() const
{
// How do I lazy-load the value?
if (peeked == '\0')
{
peeked = source.front;
// ERROR, popFront isn't const...
source.popFront();
}
return peeked;
}
}
If this isn't because of transitivity, then what is it? If only source
wasn't implicitly const (and it wouldn't be in C++, since it'd be a
const pointer to a non-const object) then this would be a piece of cake.
I run into this problem and similar ones so often that it's driven me
away from D, as much as I was a fan. If you have a nice solution then
please let me know.
