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  1. class B;
  2. class C;
  3.  
  4. class A{
  5. public:
  6.     virtual bool operator<(const A & object) const = 0; // I assume you only care about B and C
  7.     virtual bool operator<(const B & object) const = 0; // I assume you only care about B and C
  8.     virtual bool operator<(const C & object) const = 0; // I assume you only care about B and C
  9. };
  10.  
  11. class B: public A{
  12. public:
  13.     virtual bool operator<(const A & object) const
  14.     {
  15.         // do a second bind, now that we know this is type B. Negate cause we
  16.         // are switching the operands.
  17.         return !object.operator<( (const B&)*this);
  18.     }
  19.     virtual bool operator<(const B & object) const
  20.     {
  21.         return true;
  22.     }
  23.     virtual bool operator<(const C & object) const
  24.     {
  25.         return true; // B is always < than C right?
  26.     }
  27. };
  28.  
  29. class C: public A{
  30. public:
  31.     virtual bool operator<(const A & object) const
  32.     {
  33.         // do a second bind, now that we know this is type C. Negate cause we
  34.         // are switching the operands.
  35.         return !object.operator<( (const C&)*this);
  36.     }
  37.     virtual bool operator<(const B & object) const
  38.     {
  39.         return false; // C is always > then B right?
  40.     }
  41.     virtual bool operator<(const C & object) const
  42.     {
  43.         return true;
  44.     }
  45. };
  46.  
  47. int main() {
  48.    A* a1 = new B();
  49.    A* a2 = new C();
  50.    bool r = *a1 < *a2;
  51. }
Success #stdin #stdout 0s 3056KB
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https://ideone.com/mwV0wh
language:
C++14 (gcc 8.3)
created:
11 years ago
visibility:
secret

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