C++Talk.NET

Julian Hsiao · Guest

Hi,

Suppose I have a base class, defined thusly:

class Rect { /* ... */ } ;
class Point { /* ... */ };

class RegularPoly
{
public:
virtual ~RegularPoly() { }

virtual void define(Point center, int radius, int edges)
{
// ...
}

virtual void define(Point center, Point *vertexes)
{
int radius;
int edges;

// Compute the correct radius, edge based on the vertexes,
// error checking, etc.

define(center, radius, edges);
}

virtual void define(Rect bound, int edges)
{
Point center;
int radius;

// Compute the regular polygon inscribed by bound

define(center, radius, edges);
}

// More overloaded define() ...
};

Note that RegularPoly::define(Point, int, int) is the actual function that
does the defining, and all the other overloaded forms call it.

Now suppose I want a regular polygon whose edges are painted in different
colors, say it alternates between red and green:

class AltColorRegularPoly : public RegularPoly
{
public:
virtual ~AltColorRegularPoly() { }

using RegularPoly::define;

virtual void define(Point center, int radius, int edges)
{
// Make the edges alternate between red and green

RegularPoly::define(center, radius, edges);
}
};

This works out nicely, but only because I know which of the overloaded
functions is the "master" master function. In general I wouldn't know that
(unless it's documented), so I'd be forced to override all of them. The
burden would only get worse as the inheritance hierarchy deepens. Moreover,
such dependency could arise could arise with non-overloaded member functions
as well.

Other than relying on documentation, is there an idiomatic way of marking the
"master" function, so that others writing derived classes knows which to
override?

Thanks.

Julian Hsiao
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benben · Guest

Julian Hsiao wrote:

Alberto Ganesh Barbati · Guest

Julian Hsiao ha scritto:

James Kanze · Guest

Julian Hsiao wrote:

[Example deleted... I hope the rest is still
understandable.]