Re: oo programing help needed?

[Stephen Leake <stephen_leake@acm.org>]

Georg Bauhaus <sb463ba@l1-hrz.uni-duisburg.de> writes:

> shoko <shoko2004@hotmail.com> wrote:
> : i have the following:
> : ------------------------------------------
> : package one is
> :  type one  is tagged private; 
> :  type one_ptr is access all one'class;
> :  
> :   procedure set_name(name:String;this:in out one);
> :  function  get_name(this:one) return string;
> :  
> :  private
> :     type one  is tagged 
> :     record
> :         name:String(1..256);
> :     end record;
> :  
> :   
> : end one ;
> ...
> : -------------------------------------------
> : package body three is
> :   function get_name(this:three) return string
> :     s:string(1..10);
> :   begin
> :     return s+ this.name;  <-- no selector "name" for type three
> :  end get_name;
> 
> 
> In the definition of one in package one, you have chosen to
> hide .name from view. But then you select a .name component
> from within the body of package three, which as a package
> is just any package, and thus cannot see the private
> part of package one. (You could use get_name in three
> because it is not in the private part of one. This might
> be a good thing to do anyway as it respects the contract
> for dealing with ones using one's public operations.)

Or, you can make packages Two and Three child packages of One; then
they have visibility to the private part of One.

Which approach is correct depends on what your full application is.

-- 
-- Stephe