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  1. #include<iostream>
  2. using namespace std;
  3.  
  4. template<typename ClassName, typename ClassMethodType>
  5. struct HasMethod
  6. {
  7.   template<typename Type, Type Object>
  8.   struct Contains;
  9.  
  10.   template<typename Class, typename MethodType>
  11.   static char Check (Contains<MethodType, &Class::size>*);
  12.   template<typename Class, typename MethodType>
  13.   static long Check (...);
  14.  
  15.   static const bool value = (sizeof(Check<ClassName,ClassMethodType>(0)) == sizeof(char));
  16. };
  17.  
  18. struct X { 
  19.   size_t size () const { return 0; }
  20. };
  21. struct Y {
  22.   size_t size () { return 0; }
  23. };
  24. struct Z {
  25.   size_t size__ () { return 0; }
  26. };
  27.  
  28. int main ()
  29. {
  30.   cout << "HasMethod<X,size_t (X::*)() const>::value = " << HasMethod<X,size_t (X::*)() const>::value << endl;
  31.   cout << "HasMethod<X,size_t (Y::*)() const>::value = " << HasMethod<Y,size_t (Y::*)() const>::value << endl;
  32.   cout << "HasMethod<X,size_t (Z::*)() const>::value = " << HasMethod<Z,size_t (Z::*)() const>::value << endl;
  33. }
  34.  
Success #stdin #stdout 0.02s 2724KB
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stdin
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Standard input is empty
stdout
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HasMethod<X,size_t (X::*)() const>::value = 1
HasMethod<X,size_t (Y::*)() const>::value = 0
HasMethod<X,size_t (Z::*)() const>::value = 0
https://ideone.com/8W5wdT
language:
C++ (gcc 8.3)
created:
11 years ago
visibility:
public

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