Re: Accessibility Levels and Library-Level Units

[mockturtle <framefritti@gmail.com>]

This came to my mind just after clicking "Post"...

About the fact that   Accessibility_Level_Test is the "main:" I think (but I never tested it) that you could have two legal Ada codes, one that uses Accessibility_Level_Test as "main" and the other that uses it as a "normal" procedure.  (For example, if you use GNAT, the fact that a procedure is a "main" it is written in the project file, not in the Ada source.)  Maybe it is because of this that you cannot exploit the fact that Accessibility_Level_Test is the main.

Riccardo


On Tuesday, September 24, 2013 8:36:43 PM UTC+2, Eryndlia Mavourneen wrote:
> I have a package that defines a single procedure access type:
> 
> 
> 
>    1. package Accessibility_Level_Def is
> 
>    2.   pragma Pure;
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>    3.   type Proc_Type is access procedure (An_Str : String);
> 
>    4. end Accessibility_Level_Def;
> 
> 
> 
> I have a main program which references it (and another package):
> 
> 
> 
>     1. with Ada.Text_IO;                        use Ada.Text_IO;
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>     2. with Accessibility_Level_Def;            use Accessibility_Level_Def;
> 
>     3. with Accessibility_Level_Implementation; use Accessibility_Level_Implementation;
> 
>     4. procedure Accessibility_Level_Test is
> 
>     5.    procedure Test (Text : String);
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>     6.    procedure Test (Text : String) is
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>     7.    begin
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>     8.       Put_Line ("in Test");
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>     9.    end Test;
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>    10. 
> 
>    11.    The_Proc : Proc_Type;
> 
>    12. begin
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>    13.    The_Proc := Test'Access;
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>    14.    Sub (Proc => The_Proc);
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>    15. end Accessibility_Level_Test;
> 
> 
> 
> Gnat 2012 (on Ubuntu) gives the error on line 13:
> 
> 
> 
>    "Subprogram must not be deeper than access type."
> 
> 
> 
> I thought I understood accessibility levels, at least, I understood the examples I have found.  Yet, this example appears to not have the same issues:
> 
> 
> 
> 1) All the units -- packages and procedure -- are at library level.
> 
> 2) The procedure is statically defined and is not going to be 
> 
>    deallocated until the program exits.
> 
> 
> 
> This is very frustrating and would seem to preclude the definition of a procedural access type in a separate definitions package.  The Implementation package (defining procedure Sub but not shown) compiles nicely, btw.
> 
> 
> 
> Is this a problem with Gnat?  If not, how can I do what I want to do?  The attribute Unchecked_Access is not available for subprogram access types.
> 
> 
> 
> -- Eryndlia (KK1T)