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From: Simon Wright <simon@pushface.org>
Newsgroups: comp.lang.ada
Subject: Default values
Date: Sun, 25 Dec 2016 09:23:14 +0000
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Date: 2016-12-25T09:23:14+00:00
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Given

   with Ada.Real_Time;

   package Sbus.IMU is

      subtype Radians_Per_Second is Float;
      subtype Acceleration is Float;
      subtype Milligauss is Float;

      type Update (Magnetometer_Data_Present : Boolean := False) is record
         Time_Valid : Ada.Real_Time.Time;

         Gx, Gy, Gz : Radians_Per_Second;
         Ax, Ay, Az : Acceleration;

         case Magnetometer_Data_Present is
            when True =>
               Mx, My, Mz : Milligauss;
            when False =>
               null;
         end case;
      end record;

      protected Updater is
         procedure Put_New_Data (Data : Update);
         entry Get_New_Data (Data : out Update);
         procedure Get_Latest_Data (Data : out Update);
      private
         New_Data_Present : Boolean := False;
         Latest_Data : Update := (others => <>);
      end Updater;

   end Sbus.IMU;

is the line

         Latest_Data : Update := (others => <>);

legal? If so, what does it mean? (I've looked at the ARM for Record
Aggregates, 4.3.1, and Record Types. 3.8, and am no wiser).

I do realise that I need to put some default initializations in (or else
supply a proper initialization for Latest_Data!)