/* The following code example is taken from the book * "C++ Templates - The Complete Guide" * by David Vandevoorde and Nicolai M. Josuttis, Addison-Wesley, 2002 * * (C) Copyright David Vandevoorde and Nicolai M. Josuttis 2002. * Permission to copy, use, modify, sell and distribute this software * is granted provided this copyright notice appears in all copies. * This software is provided "as is" without express or implied * warranty, and with no claim as to its suitability for any purpose. */struct SizeOverOne { char c[2]; };template<typename T,         bool convert_possible = !CompoundT<T>::IsFuncT &&                                 !CompoundT<T>::IsArrayT>class ConsumeUDC {  public:    operator T() const;};// conversion to function types is not possibletemplate <typename T>class ConsumeUDC<T, false> {};// conversion to void type is not possibletemplate <bool convert_possible>class ConsumeUDC<void, convert_possible> {};char enum_check(bool);char enum_check(char);char enum_check(signed char);char enum_check(unsigned char);char enum_check(wchar_t);char enum_check(signed short);char enum_check(unsigned short);char enum_check(signed int);char enum_check(unsigned int);char enum_check(signed long);char enum_check(unsigned long);#if LONGLONG_EXISTS  char enum_check(signed long long);  char enum_check(unsigned long long);#endif  // LONGLONG_EXISTS// avoid accidental conversions from float to intchar enum_check(float);char enum_check(double);char enum_check(long double);SizeOverOne enum_check(...);    // catch alltemplate<typename T>class IsEnumT {  public:    enum { Yes = IsFundaT<T>::No &&                 !CompoundT<T>::IsRefT &&                 !CompoundT<T>::IsPtrT &&                 !CompoundT<T>::IsPtrMemT &&                 sizeof(enum_check(ConsumeUDC<T>()))==1 };    enum { No = !Yes };};