bind_refs_front() 

template<class Fn, convertible_to_weak_ref... Args>
auto bind_refs_front(Fn&&, Args&&...);

This function is similar to std::bind_front(), however:

  • it calls make_weak_ref() on Args... before storing them in the functor
  • it calls lock_weak_ref() on the stored arguments before invoking Fn
  • it does not call Fn unless all the strong references are truthy
  • it passes the live strong references to Fn, along with any other arguments at runtime

If multiple references are bound, they do not need to be similar types; they just need to all be convertible_to_weak_ref.

Example 

auto foo = std::make_shared<std::string_view>("foo");
auto bound = bind_refs_front(fn, foo);
bound(123); // invokes `fn(foo, 123)`

// As `bound` stores a `weak_ref`, this sets the `shared_ptr`'s reference count
// to 0...
foo.reset(nullptr);
// ... and as the weak_refs are now expired, this *does not* call `fn`:
bound(123);