creation of a set of segments, please help

[aaragon]

Hello everybody,

I have an interesting problem for which I still don't have a solution.
Imagine that you're working with points in two-dimesional space, so
the point class should be (simplifying):

class Point {

double x_,y_;

public:

Point(double x, double y) : x_(x), y_(y) {}
// other constructors and member functions
};

Now, imagine that you're also working with segments in 2D. A segment
consists of its endpoints:

class Segment {

Point source_, target_;
public:
Segment(const Point& s, const Point& t) : source_(s), target_(t)
{}
// other constructors and member functions
};


Now, I want to enforce that if I have points P1, P2, the segment P1-P2
is the same as the segment P2-P1. That is, the orientation of the
segment doesn't matter so as long as the endpoints are the same, the
segments are equal. This could be enforced by operator== in the
Segment class:

bool Segment::operat or==(const Segment& s)
{ return ((source_ == s.source_ && target_ == s.target_) || (target_
== s.source_ && source_ == s.target_)); }


Now, I would like to create a set of segments. Of course, the segment
does not have to have duplicates. However, sets are defined by using
operator< which is not defined here.

So the question is, how do I create a std::set of segments? Any ideas?
I could just write operator< so that it compares the smaller point
from both segments, but I thought that someone could have a better
solution.

Thank you all,

aa