-- Illustrates variant records

with ada.text_io; use ada.text_io;
with ada.integer_text_io; use ada.integer_text_io;
procedure variant is

    type PaymentType is (Cash, Check, Credit);

    -- The_Type is called the discriminant of the type
    type Transaction(The_Type: PaymentType := Cash) is record

        Amount: Integer;

        case The_Type is
            when Cash =>
                Discount: boolean := false;
            when Check =>
                CheckNumber: Positive;
            when Credit =>
                CardNumber: String(1..5);
                Expiration: String(1..5);
        end case;

    end record;

    t: Transaction;   -- Default is cash transaction
begin

    -- All transactions have an amount field
    -- put(t.amount);


    put(boolean'image(t.Discount));

    -- Cash transactions have a discount field
    if t.discount then 
        put("Give a discount"); 
    else 
        put("No discount"); 
    end if;


    -- Create a new credit transaction
    t := (credit, 100, "12345", "01/05");
    t.amount := 200;

    put(t.amount);
    put(t.CardNumber);
    put(t.Expiration);


    --put(t.CheckNumber);  -- Compiles but raises constraint error at runtime

    -- t.The_Type := check;  -- Compile error.

            -- When changing discriminant, the entire record must be assigned.
end variant;