Re: Design - cyclic dependencies

[kevin cline <kevin.cline@gmail.com>]

On Oct 26, 7:26 am, Maciej Sobczak <see.my.homep...@gmail.com> wrote:
> Consider:
>
> --  a.ads:
> package A is
>    type T is new Integer;
>    procedure P;
> end A;
>
> --  a.adb:
> with B;
> package body A is
>    procedure P is
>       X : T;
>    begin
>       B.P (X);
>    end P;
> end A;
>
> --  b.ads:
> with A;
> package B is
>    procedure P (X : A.T);
> end B;
>
> --  b.adb:
> package body B is
>    procedure P (X : A.T) is
>    begin
>       null;
>    end P;
> end B;
>
> There are two logical modules A and B, implemented as packages.
> There is no cyclic dependency between the specifications of these
> packages and the code is legal.
> Still, there is a design-level cyclic dependency between the whole
> modules in the sense that A depends on B (A calls some operation of B)
> and that B depends on A (B uses some type from A).
>
> Being legal does not imply being good and therefore I ask: do you
> consider this kind of design-level cyclic dependency to be acceptable?

I have no idea what you mean by 'logical module' or 'design-level
cyclic dependency'.  But circular package dependencies are never
acceptable to me.  I would either combine A and B into a single
package, or else break the circularity by moving T into B.