Re: friend classes in ada95

["John J. Rusnak" <john.rusnak@mindspring.com>]

Stefan Folkesson wrote:

> In ADA95, is there a way to make the private part of one class
> accessable from another (see friend classes in C++)?
>
> The reason I wonder this is because I want to apply the 'Iterator
> Pattern' in my design. This demands that the Iterator object can access
> the attributes of the Aggregate object.
>
> Is this possible? Is there a pragma to supress the access check or do I
> have to declare the attributes of the Aggregate class in the public part
> of the specification.
>
> /Stefan

Yes, and no pragma is needed.

In fact,  a class has no control (that I am aware of) of who its "friends"
are.  The way to implement a friend relationship is to use a child
package.  A child package automatically has visibility into the private
parts of its parent's spec.  The implementation of a friend class through a
child package does involve a tighter coupling of the class and its
"friend", but this is a good thing.  One should only implement a friend
relationship if there is a strong need (and a need for strong coupling
between the classes).

-John