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	#include <iostream>
	#include <vector>
	using namespace std;
 
    struct TaskInterface {
        virtual void Do() = 0;
        virtual ~TaskInterface() {}
    };
 
    template<class Impl>
    class TaskBase 
    : public TaskInterface {
        virtual void Do() {
            DoDerivedImpl();
        }
    private:
        void DoDerivedImpl() {
            static_cast<Impl*>(this)->DoImpl();
        }
 
        void DoImpl() {
             // Issue a static_assert error here, that there's no appropriate overridden
             // implementation of DoImpl() available:
             static_assert(static_cast<Impl*>(this)->DoImpl != TaskBase<Impl>::DoImpl, "TaskBase requires an appropriate implementation of DoImpl()");
        }
    };
 
    class TaskType1 : public TaskBase<TaskType1> {
    public:
        void DoImpl() {
            cout << "TaskType1::DoImpl()" << endl;
        }
    };
 
    class TaskType2 : public TaskBase<TaskType2> {
    public:
        void DoImpl() {
            cout << "TaskType2::DoImpl()" << endl;
        }
    };
 
    class TaskType3 : public TaskBase<TaskType3> {
    };
 
	int main() {
	    std::vector<TaskInterface*> tasks;
	    TaskType1 t1;
	    TaskType2 t2;
	    TaskType3 t3;
	    tasks.push_back(&t1);
	    tasks.push_back(&t2);
	    tasks.push_back(&t3);
 
	    for(std::vector<TaskInterface*>::iterator it = tasks.begin();
	        it != tasks.end();
	        ++it) {
	        	(*it)->Do();
        }
	}

prog.cpp: In instantiation of ‘void TaskBase<Impl>::DoImpl() [with Impl = TaskType3]’:
prog.cpp:18:13:   required from ‘void TaskBase<Impl>::DoDerivedImpl() [with Impl = TaskType3]’
prog.cpp:14:27:   required from ‘void TaskBase<Impl>::Do() [with Impl = TaskType3]’
prog.cpp:59:2:   required from here
prog.cpp:24:61: error: invalid use of member function (did you forget the ‘()’ ?)
              static_assert(static_cast<Impl*>(this)->DoImpl != TaskBase<Impl>::DoImpl, "TaskBase requires an appropriate implementation of DoImpl()");
                                                             ^
prog.cpp:24:61: error: invalid use of member function (did you forget the ‘()’ ?)

Standard output is empty