Question

I am unable to compile the below program in VS2010. Keeps compiling endless and got into heap not available. Any help is much appreciated.

#include <iostream>

class function_t
{
public:
    virtual void operator ()()=0;
};

class greet_t : public function_t
{
public:
    virtual void operator()(){ std::cout << "hello world" << std::endl;}
};

template<int count, function_t** f> class loop_t
{
public:
    static inline void exec()
    {
        (*(*f))();
        loop_t< count-1, f>::exec();

    }
};

function_t* f;
int _tmain(int argc, _TCHAR* argv[])
{
    f = new greet_t();
    loop_t<1, &f>::exec();

    return 0;
}

Answer 1

I believe the problem is in your template code:

template<int count, function_t** f> class loop_t
{
public:
    static inline void exec()
    {
        (*(*f))();
        loop_t< count-1, f>::exec();

    }
};

Notice that you instantiate this inner template:

loop_t< count-1, f>::exec();

The problem is that you’ve never defined a partial specialization of loop_t that terminates when the loop counter reaches some value (say, zero), and so the compiler just keeps on instantiating more and more versions of loop_t with lower and lower values of count until it reaches an internal limit and reports an error. To fix this, you should introduce a partial specialization of loop_t to halt when the counter hits some value (probably zero):

template<function_t** f> class loop_t<0, f>
{
public:
    static inline void exec()
    {
        // Empty
    }
};

Hope this helps!