Multiple virtual inheritance

Well I had a question in my mind so I can put it here as well...

By the topic I mean structure like this:

class A

class B1 : virtual public A
class B2 : virtual public A

class C : public B1, public B2

I've been familiar to multiple virtual inheritance a while, and I've never run into any situation where it would've been needed. There has always been a simpler and working solution. Nor I've never thought of any possible situation where it'd been come handy. So could somebody give me an example or ideas where multiple virtual inheritance is needed.

No code needed at all, just ideas and descriptions. Thanks.

>>could somebody give me an example or ideas where multiple virtual inheritance is needed.

iostream uses multiple inheritance and virtual base classes. Iostream is derived from both istream and ostream, and both istream and ostream are derived from ios.

class ios { . . . }; // base class
class istream : virtual public ios { . . . }; // derived
class ostream : virtual public ios { . . . }; // derived
class iostream : public istream, public ostream { . . . }; // derived

I can't say such a thing is ever needed, but it is a tool with an appropriate built-in safegaurd.

hth,

Forgive the unregistered response. I was unaware my user name would post as "unregistered."

My apologies,

Ted

if i'm ever doing something close to this i usually turn around.. in my opinion i'm just destroying the beauty of encapsulation. (at least for the kinda stuff i do)