Re: Help for correct class structure

From:

me.devilspride@gmail.com

Newsgroups:

comp.lang.c++

Date:

Sat, 5 Apr 2008 16:07:39 -0700 (PDT)

Message-ID:

<318d1f0f-9195-4ac6-acf2-b6ea277942e2@m36g2000hse.googlegroups.com>

On Apr 5, 5:20 pm, tragomaskhalos <dave.du.verg...@logicacmg.com>
wrote:

On 5 Apr, 21:08, me.devilspr...@gmail.com wrote:

On Apr 4, 9:34 pm, me.devilspr...@gmail.com wrote:

On Apr 4, 8:52 pm, "Jim Langston" <tazmas...@rocketmail.com> wrote:

me.devilspr...@gmail.com wrote:

On Apr 4, 7:28 pm, "Jim Langston" <tazmas...@rocketmail.com> wrote=

me.devilspr...@gmail.com wrote:

Hi,

I have two classes A and B as follows.
A has member data X and member functions P, Q, R. All P,Q,R acce=

ss X

and Q calls P.
B is a derived class of another Class(which I don't go into) wit=

member functions D, E.

P in A calls D in B.
D in B calls Q, R in A.

It's a big recursion. Everything works if I move D,E to class A.=

But

how do I achieve above as value of X need to be used through the=

whole program execution? I wanted to know if what I am trying to=

accomplish is something doable or I need to redesign my class
structures.

Thanks

How about showing some actual code? Even something like:

class A
{
int X;
public:
P() {}
Q() {}
// ...

};

etc..

What your'e trying to describe in words is not clear.

--
Jim Langston
tazmas...@rocketmail.com

I am sorry for that

class A {
   int X;
public:
   P() { Q(); }
   Q() { D(); R(); }
   R() { uses X }
};

class B: public someclass {
   //inherited data from someclass
public:
   D() {
       Q(); //end condition for recursion depends on X
       R();
   }
};

I can't create D() in A as D() access private data in B. But D() c=

alls

both Q() and R() and value of X has to be same everywhere. i.e. R(=

)

called from D access the same X value that was used by class A. I
guess I need to pass around this pointer of A's object or X. I gue=

it shouldn't be difficult but I am just blocked.
Hope this helps.

There is no relationship between A and B in your code. A does not=

create an

instance of B, or B A, A does not derive from B, nor B A. How doe=

s Q know

which instance of B to call D for? How does D know which instance=

of A to

call Q for? You either have to pass a B to A and/or an A to B.
class A {
{
   int X;
public:
   P(B& b) { Q( b ); }
   Q(B& b) { b.D( this ); )
   R( ) { uses X )

};

class B: public someclass {
public:
   D( A& a ) {
      a.Q( this );
      a.R();

}

--
Jim Langston
tazmas...@rocketmail.com

Thanks for the reply, that actually was my problem. Actually in my
case there will be just one instance of A and B. But there isn't just
one class B, there are lots of classes derived from a parent class. I
am actually creating objects for these classes, kind of linked list. A=

has functions for creating a list, but it may be nested that's why
there is a recursion. I guess passing A to B in my case is good. Thank=

you.

I still have some problems, Here A creates an instance of B and calls
member function of B.

///A.h
class A {
{
   int X;
public:
   P() { Q(); }
   Q() {
      R();
      bb = new B();
      bb.D( this ); )
   R() { uses X )

};

///B.h
class B: public someclass {
public:
   D( A& a ) {
      a.Q();
      a.R();

};

But there is a cyclic dependency and forward declaration of A in B
doesn't work. What should I do?
Any help would be very appreciated. Thanks.- Hide quoted text -

- Show quoted text -

You're thinking in Java/C# terms - separate the interface from
the implementation and all will be well:

// A.h
class A {
    int X;
public:
    void Q();
    void R();

};

///B.h
class B: public someclass {
public:
   D( A& a );

};

//A.cpp
#include "A.h"
#include "B.h"
void A::Q() {
       R();
       bb = new B();
       bb.D( this );}

void A::R() { uses X }

//B.cpp
#include "B.h"
#include "A.h"
void B::D( A& a ) {
      a.Q();
      a.R();

}

OK, but adding header files that way wouldn't cause any problems. I
did the same but got errors like - "C++ forbids declaration with no
type". But I will again try, Thanks.