Properly compare elements

Properly compare elements

If you have "virtual operator <" in a base class and a derived
class and each takes a reference of its own class as an arugment
then the function in the derived class hides the one in the base
class and does not override is as the signatures do not match:

class base {
public:
  bool virtual operator <(const base &cmp);
};
class derived: public base {
public:
  bool virtual operator <(const derived &cmp);
};

If two instances of base are compared then base::operator< is called:

base *p1, *p2;
if (*p1 < *p2) // calls base::operator<

git-svn-id: https://matroska.svn.sourceforge.net/svnroot/matroska/trunk/libmatroska@62 a6f86f6d-0131-4f8e-9e7b-e335508773d5