Another composition

[fog]

class A has its children/derived classes B and C. class D is supposed to be
contained inside both B and C.

Is the code right for the above requirement?
class A
{
D d;
};

class B : public A;
class C : public A;

Now should all public and protected members in D be accessible to all
members of B and C?
Is this a good design?
Thanks for your help!

 

[Claudio Puviani]

class A has its children/derived classes B and C. class D is supposed to be
contained inside both B and C.

Is the code right for the above requirement?
class A
{
D d;
};

class B : public A;
class C : public A;

Now should all public and protected members in D be accessible to all
members of B and C?
Is this a good design?

Good design limits the visibility of the internals of a class as much as
possible, even to its descendents. Therefore, no, exposing the internals of A
would not be good design.

Claudio Puviani

 

[John Harrison]

class A has its children/derived classes B and C. class D is supposed to be
contained inside both B and C.

Is the code right for the above requirement?
class A
{
D d;
};

class B : public A;
class C : public A;

Seems OK to me.

Now should all public and protected members in D be accessible to all
members of B and C?

No they shouldn't. There's no inheritance of B from D or of C from D, so
there is no automatic access to D's members from B or C.

Is this a good design?

That depends entirely on what you are trying to do. Good design doesn't
exist in the abstract.

john

 

[velthuijsen]

class A has its children/derived classes B and C. class D is supposed to be

contained inside both B and C.

Is the code right for the above requirement?
class A
{
D d;
};

class B : public A;
class C : public A;

Now should all public and protected members in D be accessible to all
members of B and C?
Is this a good design?
Thanks for your help!

Seeing that d is declared in the private block of A neither B nor C
has access to it.