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c++c++20c++-concepts

concept std::derived_from when the argument is a smart pointer

I have a few functions like so

bool RegisterModel (std::shared_ptr<DerivedA> model) { }

bool RegisterModel (std::shared_ptr<DerivedB> model) { }

and i would like to make use of c++ 20 concepts and implement it like this:

bool RegisterModel (std::derived_from<BaseClass> auto model) { }

This does not work, because i'm passing in shared pointers. It is somehow possible to require a shared pointer that holds an object derived from BaseClass?

Solution

  • Deduce the T from a std::shared_ptr<T> and constrain that:

    template<std::derived_from<BaseClass> T>
bool RegisterModel (std::shared_ptr<T> model) { }

// Or as an abbreviated function template
bool RegisterModel (std::shared_ptr<std::derived_from<BaseClass> auto> model) { }