On Monday, July 09, 2012 18:34:14 David Piepgrass wrote: > I guess D does not have 'mutable' (like C++) to override const on > methods?
No, const is actually const. You can't modify anything which is const through that reference (or pointer) to that data. Casting away const and mutating something is undefined behavior. This provides much stronger guarantees and better enables compiler optimizations. More importantly, it's required for immutabel, since a const variable could actually be immutable underneath, in which case, depending on how it was constructed (e.g. it was put in ROM), it could result in a segfault if you tried to mutate it after casting away const. http://stackoverflow.com/questions/4219600/logical-const-in-d So, const gives you much greater benefits in D than in C++, but it also comes at a much higher cost. And it comes to a bit of a head in Object, because certain function _must_ be const in Object in order to work with const (namely opEquals, opCmp, toHash, and toString), but they _can't_ be const for certain schemes (e.g. caching) to work. The open question is how to fix this (or if it even can be fixed). But the current plan is to make all 4 of those functions be @safe pure const nothrow, and that _will_ make certain schemes effectively infeasible. - Jonathan M Davis
