Daniel Keep Wrote: > > > Jason House wrote: > > Dynamic casts are pure. They don't use global state, and have the same > > output for the same reference as input. Interestingly, dynamic cast results > > are independent of intervening mutable calls... So there's even greater > > opportunity for optimization. > > What if the GC just happens to re-use that address for a different object?
I was thinking of that and tried to be careful with my wording. I guess I failed. Memoization can't occur, exactly for the reason you indicate. I was trying to say that for the life of an object, the type and type info is immutable. Since a dynamic cast only uses that immutable state, the return value does not change over the lifetime of the object. This could be used for optimizations above and beyond simple purity.
