Re: Q: Localizing type and package references

[Simon Wright <simon@pushface.org>]

Jeffrey Carter <spam.jrcarter.not@spam.not.acm.org> writes:

> On 01/05/2014 04:55 PM, b.mcguinness747@gmail.com wrote:
>>
>> --------------------------------------------------------------------------------
>> -- Types - Declarations of data types and related packages
>> --------------------------------------------------------------------------------
>> with Ada.Characters;
>> with Ada.Characters.Wide_Latin_1;
>> with Ada.Strings;
>> with Ada.Strings.Wide_Maps;
>> with Ada.Strings.Wide_Unbounded;
>> with Ada.Wide_Characters;
>> with Ada.Wide_Characters.Handling;
>> with Ada.Wide_Text_IO;
>> with Ada.Wide_Text_IO.Text_Streams;
>>
>> package Types is
>>    package Chars         renames Ada.Characters.Wide_Latin_1;
>>    package Char_Handling renames Ada.Wide_Characters.Handling;
>>    package Char_IO       renames Ada.Wide_Text_IO;
>>    package Char_Maps     renames Ada.Strings.Wide_Maps;
>>    package Char_Streams  renames Ada.Wide_Text_IO.Text_Streams;
>>    package Char_Strings  renames Ada.Strings.Wide_Unbounded;
>>
>>    subtype Char        is Wide_Character;
>>    subtype Char_String is Ada.Strings.Wide_Unbounded.Unbounded_Wide_String;
>> end Types;
>>
>> and then tried referencing this from the main program file with:
>>
>> with Types;
>> use  Types;
>>
>> with Char_Strings;
>>
>> but the compiler (Gnat 4.6) complains that there is no file called
>> char_strings.ads.  I am not sure if I have made a simple mistake that
>> can be easily corrected to make this work, or if there is a different
>> approach that I should be trying.
>
> You can only with a library-level package, one not declared in
> anything else. Char_Strings is declared in package types, so it's not
> library level and can't be withed.

So, you can either reclare package Chars etc at library level: for
example, in char_strings.ads,

   with Ada.Strings.Wide_Unbounded;
   package Char_Strings  renames Ada.Strings.Wide_Unbounded;

or you can change your main program file to say

   with Types;
   use Types;
   use Types.Chars;
   use Types.Char_Handling;
   ...

or perhaps

   with Types;
   use Types;
   procedure Main is
      use Chars;
      use Char_Handling;
      ...