entt | Gaming meets modern C++ - a fast and reliable entity | Game Engine library

While writing a mockup, with the idea of n. 1.8e9-where's-my-share m., for your "complicated registry pool" I wrote the actual could be implementation of Foo. I left in there Foo only to also give some suggestions. If you want so have more than one variable of one type you would have to change the value type of the map of course, like from std::any to std::vector. Otherwise please clarify your question more.

Ok the solution was very simple. All I did actually was I created directory in cpp folder named freetype and in that dir I've put every freetype file and just added that folder as sub directory in CMake and linked at the end and now eveyrthing works. Here is my CMake:

In C++, variables and objects of type X are actually objects of type X. They are never objects of a derived type.

Pointers to base can point at derived. Derived objects have a base class subobject in them. But a vector of foo contains actual foos.

In many C++ derived languages, variables of object type are actually pointers (often called references) to said objects. This often leads to primitive types having value semantics, while object types have reference or pointer semantics.

A vector of unique ptrs, meanwhile, can store pointers to base that point to derived.

is_move_constructible is based on the behavior of is_constructibe; it's just is_constructible. And is_constructible requires that you can do this:

With a lot of extra machinery to deal with various edge cases the code is essentially doing something like this:

The static assert that is failing is this one:

C++ (at least C++17) does not support template parameter constraints like C# does (they were proposed for C++0x as "concepts" but withdrawn). But you can have a static assert using std::is_base_of.

And as a hint to whoever consumes your library, I'd name the template parameter as TVector and TVectorItem to be clear that it expects a vector derivative.

(And I agree with the (now deleted) comment that the Service Locator pattern is an anti-pattern. There are almost always better alternatives to using the Service Locator pattern - but we'd need to know more about your application before suggesting anything).

(And if you're using Visual Studio or MSBuild and want to build a statically-evaluated or constexpr DI container builder, consider using T4 for codegen instead of C++ templates).