What is the difference between a class-wide access type and a “general” class-wide access type?
What is exactly the difference between type A is access Object’Class; and type B is access all Object’Class; In the RM and Rationale only definitions like B are used. What’s the use for A-like definitions ? (Tucker Taft answers) The only difference is that A is more restrictive, and so presumably might catch bugs that B would not. A is a “pool-specific” access type, and as such, you cannot convert values of other access types to it, nor can you use ‘Access to create values of type A. Values of type A may only point into its “own” pool; that is only to objects created by allocators of type A. This means that unchecked-deallocation is somewhat safer when used with a pool-specific type like A. B is a “general” access type, and you can allocate in one storage pool, and then convert the access value to type B and store it into a variable of type B. Similarly, values of type B may point at objects declared “aliased.” When using class-wide pointer types, type conversion is sometimes used for
