Subj : Re: Challenge: Multithreading & Synchronization
To   : comp.programming.threads
From : Sergei Organov
Date : Wed May 18 2005 09:13 pm

"Uenal Mutlu" <520001085531-0001@t-online.de> writes:
> "Sergei Organov" wrote
> > "Uenal Mutlu"  writes:
> > > // non-recursive mutex:
> > > class mutex
> > > {
> > > public:
> > >   mutex()               { /*..*/ }
> > >   ~mutex()              { /*..*/ }
> > >   void lock()           { /*..*/ }
> > >   void unlock()         { /*..*/ }
> > >   [...]
> > > };
> > >
> > > // recursive mutex:
> > > class rmutex : public mutex
> > > {
> > > public:
> > >   rmutex()        { /*..*/ }
> > > };
> >
> > Do you understand that (public) derivation of rmutex from mutex is
> > broken OO design in the first place?
> 
> Says who?

Me.

> Can you also give the exact reason what is wrong?

Absence of "is-a" relationship between them. Square and rectangle
dilemma revisited. I'm not going to go into more details here as this is
an off-topic for this group.

> Just imagine a flag set in the ctor of rmutex for enabling rmutex
> functionality in mutex.

Broken design can't be fixed in implementation.

> Everything clear now?

Yeah, broken design drives you to broken implementation.

> > Anyway, why do you mix OO-issues that you don't seem to understand well,
> > C++ issues that you don't seem to understand well, and threads related
> > issues that you don't seem to understand well in a single challenge?
> 
> Says who? Give facts, examples, not such nothing-saying empty phrases.

It's you who did mix multiple things in your "challenge" most of which
are off-topic for this newsgroup and that's unproductive. It shows your
inability or unwillingness to clearly and politely describe your primary
concern.

> The code is for illustration purposes, to describe the problem; it's
> just a skelleton, as is written in the text. You shall find your own
> solution for the problem.

No, I shall not. Anyway, the only problem I see is broken design of your
skeleton resulting in the "problem" you challenge others to fix, so the
solution is to redesign, but then there will be no "problem".

-- 
Sergei.

.