Re: A good Point/Size implementation? Re-using with different names
JiiPee <no@notvalid.com> wrote in news:VFBiw.132827$oJ1.96657@fx28.am4:
I was just thinking it (as a mathematician), and you are actually
right! Point is actually a one dimensional thing, and vector is in 2
dimension. So probably the correct representation would be:
class Point
{
int x,y;
void setPos(int newX, int newY) {x=newX, y=newY}
// ... other 1 demensinal functions
};
class Vector : public Point
{
As you just said, Vector is not a Point. Thus it makes no sense to derive
Vector (publicly) from Point (Liskov principle is violated!). Your Vector
just inherited the setPos() member function which now can be called on
it. What would it mean? A mathematical vector either does not have any
position, or maybe it has two of them (start and end), if that's what you
want to describe.
IOW, there is no need to abuse inheritance just to avoid code
replication. There are other ways to deal with code replication, starting
from extracting the code into a separate ordinary function.
hth
Paavo
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