Re: Can you use arrays from another package ?

[byhoe@greenlime.com (Adrian Hoe)]

Dale Stanbrough <dstanbro@bigpond.net.au> wrote in message news:<dstanbro-23D11A.09373422052002@mec2.bigpond.net.au>...
> Jon wrote:
> 
> > say the main program is calle MAIN.ADB
> > 
> > and uses 2 packages X and Y
> > 
> > if there is an array of records in X called A.
> > 
> > how do i use the array A in Y ?
> > 
> > e.g
> > 
> > package body X is
> >     type R is record
> >         hi : string;
> >         bye : integer;
> >     end record;
> > 
> >     A : array(1..10) of R;
> > 
> > end X;
> > 
> > 
> > now in Y, how do i use that array ? ive tried this :
> 
> you need a "with, use" clause at the start of either 
> Y's package spec, or it's package body.
> 
> You'll also need to wrap up the call to get inside
> a procedure...
> 
> e.g.
> 
> 
>   with X; use X;
> > package body Y is
> 
> procedure Get_Hi is
> begin
> >     get( X.A(1).hi );
> end;
> 
> > 
> > end Y;
> 
> 
> That's how to get it working; however i think it's a bad
> design. My design rule is "never declare variables in a
> package spec".
> 
> The declaration of A would be better in Main, and then
> you pass it into procedure Get_Hi as a parameter.
> 
> A big mistake that people make it to treat packages as
> objects - a good way to view them is just as a place where
> type declarations and subprograms go.
> (this is not quite the only way to view them, but it's a 
> good first step).
> 
> 
> Dale



SOmetimes it is difficult to say which is bad design. It depends on
the purpose and what is your approach in designing your software.

One still can have array A declared in package spec. In some cases,
you would want to declare private (or declare in the package body) and
have a procedure to read/write to the array. You hide it away from
other package but provide a nice way for access.

Sometimes, you just need to declare it public.


-- 
                                       -- Adrian Hoe
                                       -- http://adrianhoe.com