Re: Trying to declare an array from the heap from inside a record declaration

[Robert Eachus <rieachus@comcast.net>]

On Friday, November 10, 2017 at 3:10:46 AM UTC-5, AdaMagica wrote:

> Because Ada syntax does not allow it.
> 
> The question should be: Why does Ada not allow this? Ask the language lawywers! (I myself am not in favour of this idea (renamings inside a record).)

-- Probably because the result would not be what the user wants.  If you
-- allocate the array on the heap:

    X_Ptr : constant Real_Vector_Access := new Real_Vector(M .. N); 

-- You can then create a record containing 'X':

    type Foo is record
      X: Real_Vector_Access := X_Ptr;
    end record;

-- And you have data on the heap.  If you want to access elements of X_Ptr
-- incuding to assign to them Foo.X(1,2) works. If you want to create a copy
-- of X_Ptr.all (or Foo.X.all) you need the all.  If you just want to copy
-- the pointer, no .all, and that is probably what you should be doing
-- anyway.  I assume you put the object on the heap because it was too big
-- to fit on the stack, or you wanted to pass it around (in a compact form).