pragma Implemented (procedure_LOCAL_NAME, implementation_kind); implementation_kind ::= By_Entry | By_Protected_Procedure | By_Any
This is an Ada 2012 representation pragma which applies to protected, task and synchronized interface primitives. The use of pragma Implemented provides a way to impose a static requirement on the overriding operation by adhering to one of the three implementation kids: entry, protected procedure or any of the above.
type Synch_Iface is synchronized interface; procedure Prim_Op (Obj : in out Iface) is abstract; pragma Implemented (Prim_Op, By_Protected_Procedure); protected type Prot_1 is new Synch_Iface with procedure Prim_Op; -- Legal end Prot_1; protected type Prot_2 is new Synch_Iface with entry Prim_Op; -- Illegal end Prot_2; task type Task_Typ is new Synch_Iface with entry Prim_Op; -- Illegal end Task_Typ;
When applied to the procedure_or_entry_NAME of a requeue statement, pragma Implemented determines the runtime behavior of the requeue. Implementation kind By_Entry guarantees that the action of requeueing will proceed from an entry to another entry. Implementation kind By_Protected_Procedure transforms the requeue into a dispatching call, thus eliminating the chance of blocking. Kind By_Any shares the behavior of By_Entry and By_Protected_Procedure depending on the target's overriding subprogram kind.