【C++】CRTPによる静的インターフェースクラスはライブラリ実装において不適切+解決法 ref: http://qiita.com/Riyaaaa_a/items/a9af401520f238f45b80

file0.cpp

template<class T>
class Base;

class Derived : Base<Derived>;

file1.cpp

template<class T>
class Interface{
public:
   void function(){ static_cast<T&>(this)->function(); }
};

class Derived1 : Interface<Derived1>{
public:
    void function(){ std::cout << "Derived1" << std::endl; }
};

class Derived2 : Interface<Derived2>{
public:
};

file10.txt

main.cpp:8:9: error: static_assert failed "add is not defined"
        static_assert(std::is_same<decltype(std::declval<T>().add(std::declval<int>(),std::declval<int>())),int>::value,"ad...
        ^             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
main.cpp:12:7: note: in instantiation of member function 'Interface<Derived1>::Interface' requested here
class Derived1 : public Interface<Derived1>{

file11.cpp

class Derived1 : Interface<Derived1>{
public:
    int _a;
    Derived1(){ std::cin >> _a; }
    int add(int a, int b){ return a + b; }
};

file12.txt

int main(){
002A12A0  push        ebp  
002A12A1  mov         ebp,esp  
002A12A3  sub         esp,8  
002A12A6  mov         eax,dword ptr ds:[002A4000h]  
002A12AB  xor         eax,ebp  
002A12AD  mov         dword ptr [ebp-4],eax  
    Derived1 a;
002A12B0  mov         ecx,dword ptr ds:[2A3030h]  
002A12B6  lea         eax,[a]  
002A12B9  push        eax  
002A12BA  call        dword ptr ds:[2A3038h]  
    a.add(1, 1);
    return 0;
}

file13.cpp

template <class T> inline void ignore_unused_variable_warning(T const&) {}
template <class T>
void functionRequires()
{
    void (T::*fptr)() = &T::function;
    ignore_unused_variable_warning(fptr);
}

file14.cpp

template<class T>
class Interface{     
    void constraint() {
        T t;
        t.function();
    }

    typedef void (Interface<T>::* type)();
    template <type _Tp1>
    struct Check { };
    typedef Check<& Interface<T>::constraint> _Check;
};

file15.cpp

#define CLASS_REQUIRE(TT, NS, Concept) \
typedef void (NS::Concept <TT>::* func##TT##Concept)(); \
template <func##TT##Concept _Tp1> \
struct Concept_checking_##TT##Concept { }; \
typedef Concept_checking_##TT##Concept< \
& NS::Concept<TT>::constraint> \
Concept_checking_typedef_##TT##Concept

// デフォルトコンストラクタの定義を要求する制約
template<class TT>
struct DefaultConstructible {
        void constraint() {
            TT a;
            ignore_unused_variable_warning(a);
        }
    };

template<class T>
class Interface {
CLASS_REQUIRE(T, , DefaultConstructible);
};

class myclass : Interface <myclass> {};

file2.cpp

class Interface{
public:
   virtual void function()=0;
   virtual ~Interface()=default;
};

class Derived1 : Interface{
public:
    void function(){ std::cout << "Derived1" << std::endl; }
};

class Derived2 : Interface{
public:
};

file3.cpp

int main(){
    Derived1 a;
    Derived2 b;

    a.function();
    b.function();
    return 0;
}

file4.txt

main.cpp:35:15: error: variable type 'Derived22' is an abstract class
    Derived22 b;
              ^
main.cpp:20:17: note: unimplemented pure virtual method 'function' in 'Derived22'
   virtual void function()=0;

file5.txt

main.cpp:6:21: error: non-const lvalue reference to type 'Derived2' cannot bind to a temporary of type 'Interface<Derived2> *'
   void function(){ static_cast<T&>(this)->function(); }
                    ^               ~~~~
main.cpp:23:7: note: in instantiation of member function 'Interface<Derived2>::function' requested here
    b.function();
      ^
main.cpp:6:42: error: member reference type 'Derived2' is not a pointer; maybe you meant to use '.'?
   void function(){ static_cast<T&>(this)->function(); }

file6.cpp

int main(){
    Derived1 a;
    Derived2 b;

    a.function();
    //b.function();
    return 0;
}

file7.cpp

template<class T>
class Interface{
public:
    Interface(){
        static_assert(std::is_same<decltype(std::declval<T>().function()),void>::value,"function is not defined");
    }
};

file8.txt

static_assert(std::is_same<decltype(std::is_same<std::declval<T>().関数名(std::declval<引数1>(),
                                                                         ...,
                                                                         std::declval<引数n>()),
                                                 返り値の型>::value,
              "迫真怒りのメッセージ");

file9.cpp

#include<iostream>
#include<utility>

template<class T>
class Interface{
public:
    Interface(){
        static_assert(std::is_same<decltype(std::declval<T>().add(std::declval<int>(),std::declval<int>())),int>::value,"add is not defined");
    }
};

class Derived1 : Interface<Derived1>{
public:
    double add(int a,int b){return a+b;}
};

int main(){
    Derived1 a;
    return 0;
}