Help : Circular dependency

Help : Circular dependency

[prashna]

Can anybody explain, with example, What is circular dependecy?

Thanks

Re: Help : Circular dependency

[Robert A Duff]

vashwath@rediffmail.com (prashna) writes:

> Can anybody explain, with example, What is circular dependecy?

Usually, circular dependency means something like this:

    with B;
    package A is
        ...
    end A;

    with A;
    package B is
        ...
    end B;

which is illegal in Ada.  It would be legal, however, if the "with A;"
were moved to the body of B, or the "with B;" were moved to the body of A.

- Bob

Re: Help : Circular dependency

[Jeffrey Carter]

prashna wrote:
> Can anybody explain, with example, What is circular dependecy?

with B;
package A is
    type T is (Ay, Has, Tipe, Tee);
    procedure Op (P1 : in T; P2 : in B.T);
end A;

with A;
package B is
    type T is (Bee, Has, Tipe, Tee);
    procedure Op (P1 : in T; P2 : in A.T);
end B;

A depends on B, and B depends on A.

You can remove this by moving one of the type declarations up to a 
parent package (or moving the operations to a child package):

package A is
    type T is (Ay, Has, Tipe, Tee);
end A;

with B;
package A.Ops is
    procedure Op (P1 : in T; P2 : in B.T);
end A;

with A;
package B is
    type T is (Bee, Has, Tipe, Tee);
    procedure Op (P1 : in T; P2 : in A.T);
end B;

Now A does not depend on B, and B does not depend on A.Ops, so there is 
no circularity.

-- 
Jeff Carter
"Death awaits you all, with nasty, big, pointy teeth!"
Monty Python & the Holy Grail