How to achieve “virtual template function” in C++

Question

first off: I have read and I know now that a virtual template member function is not (yet?) possible in C++. A workaround would be to make the class a template and then use

Answer 1

Virtual template function is not allowed. However you can use one OR the other here.

You could make an interface using virtual methods and implement your various animals in terms of having an eating interface. (i.e. PIMPL)

Less human intuitive would be having a non-member non-friend template function as a free function which could take templated const reference to any animal and make them eat accordingly.

For the record you don't need templates here. Pure virtual abstract method on the base class is enough to force and interface where all animals must eat and define how they do so with an override, providing a regular virtual would be enough to say all animals can eat but if they don't have a specific way then they can use this default way.