Two base classes need Inheritance?

[Immortal Nephi]

I write three classes. The name of class are A, B, and C. Class A
and Class B are inaccessible to the client. Class C is accessible to
the client.

Class B has inheritance to Class A. The member function in class B
modify data in Class A. I need to find a way how Class A can have
inheritance to Class B, but C++ Compiler does not allow it. The rule
of inheritance goes from top to the bottom.

Class A needs to have inheritance to Class B. The member function in
class A modify data in Class B.

It is the way how Class A and Class B can become one class to modify
both Class A's and Class B's data together. Class A is getting too
large over 200,000 lines. It makes easier to divide one class into
two classes for better readable C++ writing.

Class C is derived from both Class A and Class B. Here is an example
how three classes look like.

A-->B A<--B
A-------------B
\ /
\ A and B /
\ Go /
\ Down /
\ To /
\ C /
\ /
|
C

class A;
class B;
class C;

class A : // C++ Compiler disallows....
public B // class A modifies class B's data
{...};

class B : // C++ Compiler allows....
public A // class B modifies class A's data
{...};

class C :
public A, public B // class C displays both classes' data
{...};

Can you please write an example of short source code? Find a way how.

Immortal Nephi

[blargg]

Re: Two base classes need Inheritance?

In article
<63e20569-76bd-406d-a217-9a8319d44cb4@k3 0g2000hse.googl egroups.com>,
Immortal Nephi <Immortal_Nephi @satx.rr.comwro te:

[...]
class A;
class B;
class C;
>
class A : // C++ Compiler disallows....
public B // class A modifies class B's data
{...};
>
class B : // C++ Compiler allows....
public A // class B modifies class A's data
{...};
>
class C :
public A, public B // class C displays both classes' data
{...};
>
[poster wants to know how to have A and B derive from each other]

class A {
protected:
B* b;
void f1();
};

class B : public A {
public:
B() { b = this; }
void f2() { this->f1(); }
};

void A::f1() { b->f2(); }

Now A can access B via b, and B can access A members via this.

[blargg]

Re: Two base classes need Inheritance?

In article <blargg.h4g-180808152813000 1@192.168.1.4>,
blargg.h4g@gish puppy.com (blargg) wrote:

In article
<63e20569-76bd-406d-a217-9a8319d44cb4@k3 0g2000hse.googl egroups.com>,
Immortal Nephi <Immortal_Nephi @satx.rr.comwro te:
>

[...]
class A;
class B;
class C;

class A : // C++ Compiler disallows....
public B // class A modifies class B's data
{...};

class B : // C++ Compiler allows....
public A // class B modifies class A's data
{...};

class C :
public A, public B // class C displays both classes' data
{...};

[poster wants to know how to have A and B derive from each other]

>
class A {
protected:
B* b;
void f1();
};
>
class B : public A {
public:
B() { b = this; }
void f2() { this->f1(); }
};
>
void A::f1() { b->f2(); }
>
Now A can access B via b, and B can access A members via this.

Bleah, I wasn't thinking above. Just use a static_cast:

class B;

class A {
private:
B* b();
void f1();
A() { } // private to ensure all A objects are really B objects
friend class B;
};

class B : public A {
public:
void f2() { this->f1(); }
};

inline B* A::b() { return static_cast<B*( this); }

void A::f1() { b()->f2(); }

[Chris M. Thomasson]

Re: Two base classes need Inheritance?

"blargg" <blargg.h4g@gis hpuppy.comwrote in message
news:blargg.h4g-180808193859000 1@192.168.1.4.. .
[...]

>Now A can access B via b, and B can access A members via this.

>
Bleah, I wasn't thinking above. Just use a static_cast:
>
class B;
>
class A {
private:
B* b();
void f1();
A() { } // private to ensure all A objects are really B objects
friend class B;
};
>
class B : public A {
public:
void f2() { this->f1(); }
};
>
inline B* A::b() { return static_cast<B*( this); }
>
void A::f1() { b()->f2(); }

Won't invoking B::f2 go into and endless loop and blow the stack?

;^)