Re: Aliased

[Robert A Duff <bobduff@shell01.TheWorld.com>]

nblanpain@hotmail.com writes:

> So this is my sources and the compilation error :
>
> ------ Container.ads
> generic
>    type T_Item is private;
>    Static_Size : Integer;
> package Container is
>    type T_Array is array (Integer range <>) of T_Item;
>    type A_Array is access all T_Array;
>    type T_Container is tagged record
>       Obj_Array : aliased T_Array (1..Static_Size);
>       Ptr_Array : A_Array;
>    end record;
>    procedure Initialize (This : in out T_Container; Dynamic_Size : in
> Integer);
>    function P_Array (This : in T_Container) return A_Array;
> end Container;

I have a package that tries to do something similar.
Try wrapping the array in a record:

    type T_Rec(Length: Natural) is
        record
            A: T_Array(1..Length);
        end record;
    type T_Rec_Ptr is access all T_Rec;
    type T_Container is tagged record
        Obj_Array : aliased T_Rec (Length => Static_Size);
        Ptr_Array : T_Rec_Ptr;
    end record;

Then Initialize can set Ptr_Array to either "new T_Rec(Length =>
Dynamic_Size)" or "This.Obj_Array'Access".

Well, you'll want to change the names of things to make sense...
    
> ------ Container.adb
> package body Container is
>    procedure Initialize (This : in out T_Container; Dynamic_Size : in
> Integer) is
>    begin
>       if Dynamic_Size /= 0 then
>          This.Ptr_Array := new T_Array (1.. Dynamic_Size);
>      elsif Static_Size /= 0 then
>         This.Ptr_Array := This.Obj_Array'Access; --- Compilation Error
>      end if;
>    end Initialize;
>    function P_Array (This : in T_Container) return A_Array is
>    begin
>       return This.Ptr_Array;
>    end P_Array;
> end Container;
> 
> -- Compilation Error : Object subtype must statically match designated
> subtype. No local pointer cannot point to local object.

- Bob