Re: [boost] [GTL] - geometric template library - determininginterest

From: John Femiani (JOHN.FEMIANI_at_[hidden])
Date: 2007-10-08 19:34:46

> -----Original Message-----
> From: boost-bounces_at_[hidden]
[mailto:boost-bounces_at_[hidden]]
> On Behalf Of Simonson, Lucanus J
> Sent: Monday, October 08, 2007 4:17 PM
> To: boost_at_[hidden]
> Subject: Re: [boost] [GTL] - geometric template library -
> determininginterest
> 
> John Femiani wrote:
> >I think there is also something about classes with no data members.
> 
> I'm not sure what you are driving at.  Perhaps I simply don't know
this
> one.  Please enlighten me.
> 
> Luke
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------------ main.cpp -------------------

#include <iostream>

using namespace std;

struct A {};
struct B {};
struct C {};

struct ABC_composite {
    A _a;
    B _b;
    C _c;
    A& a() {return _a;}
    B& b() {return _b;}
    C& c() {return _c;}

};

struct ABC_inheritted : public A, public B, public C {
    A& a() { return * static_cast<A*>(this);}
    B& b() { return * static_cast<B*>(this);}
    C& c() { return * static_cast<C*>(this);}
};

int main()
{

    cout << "Composite: " <<  sizeof(ABC_composite) << endl;
    cout << "Inheritted: " <<  sizeof(ABC_inheritted) << endl;
    return 0;
}

--------- program output -------------

Composite: 3
Inheritted: 1

----------------------------------------

I just thought it might have something to do with why you opted for it. 

-- John