On Tue, Jul 10, 2012 at 04:58:06PM -0700, Walter Bright wrote: > On 7/10/2012 4:19 PM, H. S. Teoh wrote: > >On Tue, Jul 10, 2012 at 04:05:51PM -0700, Walter Bright wrote: > >>On 7/10/2012 4:05 PM, H. S. Teoh wrote: [...] > >Nqt in this case. The const(B) reference does not permit any of B's > >methods to mutate the members of B -- you cannot downcast a const(B) > >reference to a C reference. As far as the methods of B are concerned, > >the object is immutable. > > > >The interesting part is when C's methods override B's methods: those > >methods _can_ mutate the object, but not the members inherited from > >B. And this does not break immutability; you cannot cast const(B) to > >C, so if you start with immutable(B), it will remain immutable no > >matter what. You can't call C's methods from the const(B) reference, > >and you can't override B's methods with C's mutating methods without > >actually having a mutable C to begin with. > > > > > >T > > > > If you've found a way to mutate const and have it stay const, then > there's a hole in the typing system.
The const in const(B) applies to the B portion of the object. Just because the C portion changes, doesn't violate the const-ness of the B portion. I know this isn't how the current type system works, but perhaps it can be made to work in a way that makes sense. T -- Real Programmers use "cat > a.out".
