Emulating virtual function templates

Hallo,
first of all, let me state that I *know* that member function templates
cannot be virtual; however I need to somehow achieve something as close
to the following as possible:

// Beware! Invalid C++

struct base {
     template <typename T>
     virtual void set(T const & t) = 0;
};

struct env {
     template <typename T> void set(T const & t) { p->set(t); }

     base * p;
};

What I could come up with is the following:

struct proxy_base {
     virtual ~proxy_base() {}
};

template <typename T> struct proxy : proxy_base {
     virtual void set(T const &) = 0;
};

struct base2 {
     virtual proxy_base * get() = 0;
};

struct env2 {
     template <typename T> void set(T const & t) {
         proxy_base * pbp = p->get();
         assert(dynamic_cast<proxy<T> *>(pbp));
         static_cast<proxy<T> *>(pbp)->set(t);
     }

     base2 * p;
};

Is there any better solution?

Thank you,
Nicola Musatti

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