CODEWITHSUNDEEP
ada
Tyg13
Tyg13

Reputation: 321

Initialize constant variable of record type with all default values

Say I have a type

type Record_T is
   record
      VAR1 : integer := 1;
      VAR2 : string  := "";
   end record;

If I want to initialize a constant variable of this type, I can do it a few ways:

Null_Record : constant Record_T := (1, "");
Null_Record : constant Record_T := Record_T'(1, "");

but this forces me to specify the default values, when I already previously specified them.

I've tried all of the following, to no avail

Null_Record : constant Record_T := ();
Null_Record : constant Record_T := Record_T'();
Null_Record : constant Record_T;

But there has to be some way to do so? At least, I'd be very surprised if Ada lacked that capability.

Upvotes: 3

Views: 1333

Answers (2)

Jeffrey R. Carter
Jeffrey R. Carter

Reputation: 3358

The typical way, pre-ISO/IEC 8652:2007, presuming your type is in a package, is to declare a deferred constant in the visible part:

Null_Record : constant Record_T;

and then complete it in the private part with:

Null_Var    : Record_T;
Null_Record : constant Record_T := Null_Var;

Upvotes: 3

Tyg13
Tyg13

Reputation: 321

It looks like this should be possible in Ada 2005, using the new "default value initialization" for aggregates using the <> operator.

This would look something like

Null_Record : constant Record_T := (others => <>);

I can't see any way to do this pre-Ada 2005. Unfortunately, this isn't a solution for me, being stuck with Ada 95.

Upvotes: 8

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