Name: dbT83986 Date: 04/13/99


It would be real cute to be able to mark objects as being
Immutable (as per Strings). This means that the internal
state is not permitted to change after creation. This would
allow extra optimisations at compile time. It would then be
useful to mark objects as being Primitive objects. Only
Immutable objects should be allowed to be Primitive. Primitive
objects would have the property that if a == b, then a.equals(b)
is also true (ie the object reference is formed from the object's
internal state such that two objects with the same internal state
are actually the same object - hence the need for Immutability).

i.e.
public interface Immutable {}
public interface Primitive extends Immutable {}

Then

int, long, float, double, short, char, byte, boolean
     are all Primitive
String
     is Immutable (and should be Primitive).

You see that Primitive types are the only types that can be
dealt with properly at compile time. It would also be nice
to re-introduce the const keyword, marking any object
instance as immutable (not the class) for things like
constants and parameters!!!!
(Review ID: 56888)
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