Extensions

FredEmmott::weak_refs can be extended to support new types by creating a pair of extension classes; if you control/own the namespace containing the type, ADL is an easier alternative.

All weak_ref/strong_ref types are supported via extensions; for example, weak_refs’s built-in support for the following is via bundled extensions:

• std::shared_ptr
• C++/WinRT
• Argument-Dependent Lookup (ADL)

An ‘extension’ is just a name for a pair of template class specializations in the FredEmmott::weak_refs_extensions namespace:

#include <FredEmmott/weak_refs/extensions.hpp>

template<>
struct make_weak_ref_fn<SomeNS::SomeStrongRef> {
  auto make(auto value) {
    return somehow_convert_to_weak(value);
  }
};

template<>
struct lock_weak_ref_fn<SomeNS::SomeWeakRef> {
  auto lock(auto value) {
    return somehow_convert_to_strong(value);
  }
};

Most extensions partially specialize the classes, using C++20 concepts to match appropriate types.