34 lines
780 B
C++
34 lines
780 B
C++
template<typename T> //Detection helper struct
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struct can_eat //Detects presence of non-const member function void eat()
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{
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private:
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template<typename U, void (U::*)()> struct SFINAE {};
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template<typename U> static char Test(SFINAE<U, &U::eat>*);
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template<typename U> static int Test(...);
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public:
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static constexpr bool value = sizeof(Test<T>(0)) == sizeof(char);
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};
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struct potato
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{ void eat(); };
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struct brick
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{};
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template<typename T>
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class FoodBox
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{
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//Using static assertion to prohibit non-edible types
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static_assert(can_eat<T>::value, "Only edible items are allowed in foodbox");
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//Rest of class definition
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};
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int main()
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{
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FoodBox<potato> lunch;
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//Following leads to compile-time error
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//FoodBox<brick> practical_joke;
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}
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