guideline

Localize the currency symbol, digits separator, radix mark, and fill character in picture output.

Consider using the # character in picture layouts so that the edited numeric output lengths are invariant across currency symbols of different lengths.

with Ada.Text_IO.Editing;
package Currency is

   type Dollars is delta 0.01 digits 10;
   type Marks   is delta 0.01 digits 10;

   package Dollar_Output is
      new Ada.Text_IO.Editing.Decimal_Output
             (Num                => Dollars,
              Default_Currency   => "$",
              Default_Fill       => '*',
              Default_Separator  => ',',
              Default_Radix_Mark => '.');

   package Mark_Output is
      new Ada.Text_IO.Editing.Decimal_Output
             (Num                => Marks,
              Default_Currency   => "DM",
              Default_Fill       => '*',
              Default_Separator  => '.',
              Default_Radix_Mark => ',');

end Currency;
with Ada.Text_IO.Editing;
with Currency;  use Currency;
procedure Test_Picture_Editing is

   DM_Amount     : Marks;
   Dollar_Amount : Dollars;

   Amount_Picture : constant Ada.Text_IO.Editing.Picture 
      := Ada.Text_IO.Editing.To_Picture ("##ZZ_ZZZ_ZZ9.99");

begin   -- Test_Picture_Editing

   DM_Amount     := 1_234_567.89;
   Dollar_Amount := 1_234_567.89;

   DM_Output.Put (Item => DM_Amount,
                  Pic  => Amount_Picture);

   Dollar_Output.Put (Item => Dollar_Amount,
                      Pic  => Amount_Picture);
   
end Test_Picture_Editing;

rationale

Currencies differ in how they are displayed in a report. Currencies use different symbols of different lengths (e.g., the American $, the German DM, and the Austrian ÖS). They use different symbols to separate digits. The United States and the United Kingdom use the comma to separate groups of thousands, whereas Continental Europe uses the period. The United States and the United Kingdom use a period as a decimal point; Continental Europe uses the comma. For a program involving financial calculations that is to be reused across countries, you need to take these differences into account. By encapsulating them, you limit the impact of change in adapting the financial package.