Question

I’m trying to use Ada to print a class derived from Natural; however, I keep getting the error, prefix of "image" attribute must be a type. Google apparently knows nothing useful about this error.

Here is the simplified code which produced this error:

with Ada.Text_IO;
use Ada.Text_IO;
with Layout; use Layout;
procedure temptest is
   term : Terminator_ID;
   begin
      term := Layout.Block_GetOpposite (1, Layout.REVERSED);
   Put_Line (Item => term'Image);
   end temptest;

Here is the definition of Terminator_ID in my Layout package:type Terminator_ID is new Natural range 1 .. 40;

What is causing this error and what is the appropriate way to correct it?

Answer 1

Apparently the syntax for converting a number to string is Type_Name'Image(var_containing_value).

I changed my code to:

with Ada.Text_IO;
use Ada.Text_IO;
with Layout; use Layout;
procedure temptest is
   term : Terminator_ID;
   begin
      term := Layout.Block_GetOpposite (1, Layout.REVERSED);
   Put_Line (Item => Terminator_ID'Image (term));
   end temptest;

and it compiles fine now.