Re: Solving the data inheritance problem
Hm, what have you gained then?
This way (approximately, of the head):
class A {
protected:
class Common
{
// Something
};
virtual Common& GetData() = 0;
public:
void f()
{
GetData().f();
}
};
class B[i] : public A {
public:
void swap(B[i]& that)
{
// Advantage: now you probably remember to swap
// the common implementation also.
common_.swap(that.common_);
std::swap(myData_, that.myData_);
}
protected:
virtual Common& GetData()
{
return common_;
}
private:
Common common_;
int myData_;
};
I think using mixin classes offers another solution. A is now just a
/real/ interface with neither data nor implementation.
class A {
virtual T& GetData() = 0;
...
};
class B[i] : public A {
...all the things B[i] adds to A...
};
template <typename B>
class SharedCode : public B {
public:
SharedCode(const SharedCode&);
SharedCode& operator=(const SharedCode&);
T& GetData();
void swap(SharedCode&);
...
private:
T data_;
};
typedef SharedCode<B[0]> B[0]_leaf;
typedef SharedCode<B[1]> B[1]_leaf;
...
Very good idea! This is the same idea as in the beginning of this post,
but the boiler-plate generation is automated with templates. Btw, it now
happens that in SharedCode you must again remember to swap also the
superclass B, but the difference is that you do this only once for all
B. Great idea!
--
Kalle Rutanen
http://kaba.hilvi.org
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