Inherited constructors (templates)

From:
Johannes Bauer <dfnsonfsduifb@gmx.de>
Newsgroups:
comp.lang.c++
Date:
Thu, 21 May 2009 11:29:33 +0200
Message-ID:
<77kl7sF1gffh9U1@mid.dfncis.de>
Hello group,

I'm having a problem with inheritance and I've run out of ideas. I'm
trying to encpsulate threads in a nice(tm) way. Therefore I declared a
template class:

template <typename ArgumentType, typename ReturnType> class Thread

with a purely virtual method

virtual ReturnType Action() = 0;

of which my actual threads should inherit from:

class AddingThread : public Thread<int*, int> {
    public:
        int Action() {
            int sum = 0;
            for (unsigned int i = 0; i < 10; i++) {
                sum += Data[i];
            }
            return sum;
        }
};

Now I want to call that thing just like

int foo[10];
memset(foo, 0, sizeof(foo));
foo[5] = 9;

AddingThread t1(foo);
int result = t1.join();

The problem I get is:

threadtest.cpp: In function int main():
threadtest.cpp:23: error: no matching function for call to
AddingThread::AddingThread(int [10])
threadtest.cpp:6: note: candidates are: AddingThread::AddingThread()
threadtest.cpp:6: note: AddingThread::AddingThread(const
AddingThread&)

I can solve it, of course, by doing:

AddingThread(int *x) : Thread<int*, int>(x) { }

Where the "Thread" constructor does all the magic (i.e. actually
creating the thread and calling the trampoline to kick off "Action").
However, I do not want this redundant constructor delegation - is it
possible to tell the compiler to always use only the parent's
constructor of identical prototype if no child constructor is available?

Maybe I'm also thinking just in a very wrong way, maybe inheritance
isn't even the way to go here. Some other ideas maybe?

Kind regards,
Johannes

--
"Meine Gegenklage gegen dich lautet dann auf bewusste Verlogenheit,
verl?sterung von Gott, Bibel und mir und bewusster Blasphemie."
         -- Prophet und Vision?r Hans Joss aka HJP in de.sci.physik
                         <48d8bf1d$0$7510$5402220f@news.sunrise.ch>

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