Re: how to import a package

["markww" <markww@gmail.com>]

Hi Adam,

Thanks for your help. Now I've instantiated a list of my ppl records.
Right underneath the generic package definition I had:

    Start  : Node_Ptr;
    Last   : Node_Ptr;

but Node_Ptr is not visible. Is it no longer possible to have those two
variables declared like that?

Thanks,
Mark


Adam Beneschan wrote:
> markww wrote:
> > Hi,
> >
> > I have this snippet of code (from members here) which defines a generic
> > type:
> >
> >     generic
> >     type T is private;
> >         package P is
> >     type Node;
> >     type Node_Ptr is access Node;
> >         type Node is record
> >             Data     : T;
> >             Prev_Rec : access Node; -- points to the next record or
> > null if none exists.
> >             Next_Rec : access Node; -- points to the previous record or
> > null if none exists.
> >         end record;
> >     end P;
> >
> > Now my compiler (gnat) complains that Node, and Node_Ptr are not seen
> > by the rest of the application. Is this because they are scoped within
> > package P?
> >
> > If so, how do I 'import' the package? Right now I just stuck this at
> > the start of my main procedure:
>
> P is a generic package so you have to instantiate it.  Something like:
>
>    package Person_List is new P (T => Person_Rec);
>
> Now, Node and Node_Ptr are visible within Person_List, and the "Data"
> field in Person_List.Node will have type Person_Rec.
>
> There's no such thing as a "generic type" in Ada.
> 
>                 -- Adam