Let's consider several examples where CRTP is used to delegate behavior from the base class to the derived one.
The first example is a very simple one—for any class that provides operator==(), we want to generate operator!=() automatically as the inverse of the former:
template <typename D> struct not_equal { bool operator!=(const D& rhs) const { return !static_cast<const D*>(this)->operator==(rhs); }};class C : public not_equal<C> { int i_; public: C(int i) : i_(i) {} bool operator==(const C& rhs) const { return i_ == rhs.i_; }};
Any class that inherits from not_equal in this manner automatically acquires the not equal operator that is guaranteed to match the provided operator, equal. An observant reader might point ...
