Re: Base class returning children's data

From:
"Alessandro [AkiRoss] Re" <akirosspower@gmail.com>
Newsgroups:
comp.lang.c++
Date:
Sat, 5 Jul 2008 03:06:07 -0700 (PDT)
Message-ID:
<9ad7ee34-035c-4ebf-9d52-8789085fea38@a1g2000hsb.googlegroups.com>
On Jul 5, 2:54 am, "Alf P. Steinbach" <al...@start.no> wrote:

Well, then you run into problems if you allow variable data in those prop=

erties.

But putting that aside (just don't have that), it seems that what you're =

after

is the old concept of meta-class, like, off the cuff,


Thanks for the reply :) It gave me some ideas...

I'd prefer to avoid meta-classes, it seems a little code bloat to me
for such an easy (?) task. What about this? It seems to work, but...
Is it correct and safe?

class Base {
    // This is the function I'd like to write only once
    const int get() { return val() * 100 + 5; }
private:
    virtual int val() {
        static const int myVal = 10;
        return myVal;
    }
};

class Deri: public Base {
private:
    virtual int val() {
        static const int myVal = 20;
        return myVal;
    }
};

int main(int argc, char **argv) {
    Base *o1 = new Base(),
         *o2 = new Deri();

    cout << "O1 val: " << o1->get() << endl
        << "O2 val: " << o2->get() << endl;
    return EXIT_SUCCESS;
}

I mean, get() will always refer to polymorphic (overwritten virtual)
val()?
Actually I'm having some difficulties in figuring out *why* this
works :D

Thanks!

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