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C.7.1 The Package Task_Identification

Static Semantics
The following language-defined library package exists:
       package Ada.Task_Identification is
          type Task_ID is private;
          Null_Task_ID : constant Task_ID;
          function  "=" (Left, Right : Task_ID) return Boolean;
          function  Image        (T : Task_ID) return String;
          function  Current_Task return Task_ID;
          procedure Abort_Task   (T : in out Task_ID);
          function  Is_Terminated(T : Task_ID) return Boolean;
          function  Is_Callable  (T : Task_ID) return Boolean;
          ... -- not specified by the language
       end Ada.Task_Identification;
Dynamic Semantics
A value of the type Task_ID identifies an existent task. The constant Null_Task_ID does not identify any task. Each object of the type Task_ID is default initialized to the value of Null_Task_ID.
The function "=" returns True if and only if Left and Right identify the same task or both have the value Null_Task_ID.
The function Image returns an implementation-defined string that identifies T. If T equals Null_Task_ID, Image returns an empty string.
The function Current_Task returns a value that identifies the calling task.
The effect of Abort_Task is the same as the abort_statement for the task identified by T. In addition, if T identifies the environment task, the entire partition is aborted, See E.1.
The functions Is_Terminated and Is_Callable return the value of the corresponding attribute of the task identified by T.
For a prefix T that is of a task type (after any implicit dereference), the following attribute is defined:
For a prefix E that denotes an entry_declaration, the following attribute is defined:
Program_Error is raised if a value of Null_Task_ID is passed as a parameter to Abort_Task, Is_Terminated, and Is_Callable.
Abort_Task is a potentially blocking operation (see 9.5.1).
Bounded (Run-Time) Errors
It is a bounded error to call the Current_Task function from an entry body or an interrupt handler. Program_Error is raised, or an implementation-defined value of the type Task_ID is returned.
Erroneous Execution
If a value of Task_ID is passed as a parameter to any of the operations declared in this package (or any language-defined child of this package), and the corresponding task object no longer exists, the execution of the program is erroneous.
Documentation Requirements
The implementation shall document the effect of calling Current_Task from an entry body or interrupt handler.


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