File: protected_example.adb

```
procedure Protected_Example is 
```
```
 
```
```
   type Priorities is (High, Low); 
```
```
 
```
```
   protected Queues is 
```

      procedure Trigger (Priority : Priorities);

```
      entry     Queue   (Priorities); 
```
```
   private 
```

      Current_Priority : Priorities := Low;

      Open             : Boolean    := False;

```
   end Queues; 
```
```
 
```
```
   protected body Queues is 
```
```
 
```

      procedure Trigger (Priority : Priorities) is

```
 
```
```
      begin 
```

         Open := True; Current_Priority := PriorityTo spec
To body;

```
      end TriggerTo spec
To body; 
```
```
 
```

      entry Queue (for Priority in Priorities) when Open and then Priority = Current_Priority is

```
 
```
```
      begin 
```
```
         Open := False; 
```
```
      end QueueTo spec
To body; 
```
```
   end Queues; 
```
```
 
```

   task type Priority_Task (Priority : Priorities);

```
 
```
```
   task body Priority_Task is 
```
```
   begin 
```

      Queues.QueueTo spec
To body (Priority);

```
      if Priority = High then 
```

         Queues.TriggerTo spec
To body (High);

```
      end if; 
```
```
   end Priority_Task; 
```
```
 
```
```
   T1         : Priority_Task (Low); 
```
```
   T2, T3, T4 : Priority_Task (High); 
```
```
 
```
```
begin 
```
```
   delay 1.0; -- seconds 
```

   Queues.TriggerTo spec
To body (High);

```
   delay 1.0; -- seconds 
```
```
   Queues.TriggerTo spec
To body (Low); 
```
```
end Protected_ExampleTo spec
To body; 
```