fork download

#include <iostream>
 
    struct Cloneable
	{
	protected:
		Cloneable(){}
		Cloneable(const Cloneable &){}
	public:
		virtual ~Cloneable(){}
 
		Cloneable &operator=(const Cloneable &) = delete;
 
		virtual Cloneable *Clone() const = 0;
		static void ReleaseClone(Cloneable *&clone)
		{
			clone->ReleaseClone(), clone = /*nullptr*/0;
		}
	protected:
		virtual void ReleaseClone() = 0;
	public:
//		struct CloningException : public virtual Exception
//		{
//			CloningException(){}
//			CloningException(const char *msg) : Exception(msg) {}
//			CloningException(const CloningException &) = delete;
//			CloningException &operator=(const CloningException &) = delete;
//			virtual ~CloningException(){}
//		};
 
		template<typename InheritingClass>
		struct Auto : public virtual Cloneable
		{
			typedef InheritingClass ICT;
			virtual ICT *Clone() const
			{
				const ICT *t = dynamic_cast<const ICT *>(this);
				if(!t)
				{
//					throw CloningException();
				}
				return new ICT(*t);
			}
		protected:
			virtual void ReleaseClone()
			{
				if(!dynamic_cast<const ICT *>(this))
				{
//					throw CloningException();
				}
				delete this;
			}
		public:
			virtual ~Auto(){}
		};
	};
 
struct MyAbstractClass : public virtual Cloneable
{
    MyAbstractClass(){}
protected:
    MyAbstractClass(const MyAbstractClass &){}
public:
    virtual ~MyAbstractClass(){}
 
    MyAbstractClass &operator=(const MyAbstractClass &) = delete;
 
    virtual void Tick() = 0;
};
 
struct MyImplementationClass : public virtual MyAbstractClass, public virtual Cloneable::Auto<MyImplementationClass>
{
    MyImplementationClass(){}
protected:
    MyImplementationClass(const MyImplementationClass &){}
public:
    virtual ~MyImplementationClass(){}
 
    MyImplementationClass &operator=(const MyImplementationClass &) = delete;
 
    virtual void Tick();
 
    using Cloneable::Auto<MyImplementationClass>::Clone;
protected:
    using Cloneable::Auto<MyImplementationClass>::ReleaseClone;
};
 
void MyImplementationClass::Tick()
{
    std::cout << "Tick" << std::endl;
}
 
int main()
{
    MyImplementationClass a;
    MyAbstractClass *b = a.Clone();
    b->Tick();
    Cloneable::ReleaseClone(b);
}
 

prog.cpp:32:3: error: invalid use of incomplete type 'struct Cloneable'
prog.cpp:4:2: error: forward declaration of 'struct Cloneable'
prog.cpp: In function 'int main()':
prog.cpp:94:27: error: cannot declare variable 'a' to be of abstract type 'MyImplementationClass'
prog.cpp:71:1: note:   because the following virtual functions are pure within 'MyImplementationClass':
prog.cpp:13:22: note: 	virtual Cloneable* Cloneable::Clone() const
prog.cpp:19:16: note: 	virtual void Cloneable::ReleaseClone()
prog.cpp:97:30: error: no matching function for call to 'Cloneable::ReleaseClone(MyAbstractClass*&)'
prog.cpp:14:15: note: candidates are: static void Cloneable::ReleaseClone(Cloneable*&)
prog.cpp:19:16: note:                 virtual void Cloneable::ReleaseClone()
prog.cpp: In member function 'ICT* Cloneable::Auto<InheritingClass>::Clone() const [with InheritingClass = MyImplementationClass, ICT = MyImplementationClass]':
prog.cpp:95:34:   instantiated from here
prog.cpp:41:22: error: cannot allocate an object of abstract type 'MyImplementationClass'
prog.cpp:71:1: note:   since type 'MyImplementationClass' has pure virtual functions

Standard output is empty