c++ - Is there a proper 'ownership-in-a-package' for 'handles' available?

Question

Handles have proper semantics other than pointers. So for me an example like this (extracted from the Rule of Zero):

class module {
public:
    explicit module(std::wstring const& name)
    : handle { ::LoadLibrary(name.c_str()), &::FreeLibrary } {}

    // other module related functions go here

private:
    using module_handle = std::unique_ptr<void, decltype(&::FreeLibrary)>;

    module_handle handle;
};

using unique_ptr as an 'ownership-in-a-package' for handles is a bad example. First, it makes use of internal knowledge that the handle is a pointer type, and use this to make a unique_ptr to the basic type the "opaque" handle type builds upon.

Handles can be any type, they may be a pointer, they may be an index or who knows. Most importantly, what you have at hand (from most C API's for example) is a handle and its resource releasing function.

Is there a proper 'ownership-in-a-package' that works in handle semantics? I mean, already publicly available for one to use?

For me, unique_ptr et. al. doesn't work, I must make unnecessary assumptions about what the handle type is, when what I want is just to get an 'ownership-in-a-package' through the opaque handle type and its releasing function, solely.

It doesn't make sense for one to peer inside the handle type to make constructions upon this information. It's a handle, it should not matter.

I'll quote here the feelings of another SO user in another question's answer:

Create a specific "smart pointer" class, won't take long. Don't abuse library classes. Handle semantics is quite different from that of a C++ pointer; for one thing, dereferencing a HANDLE makes no sense.

One more reason to use a custom smart handle class - NULL does not always mean an empty handle. Sometimes it's INVALID_HANDLE_VALUE, which is not the same.

Disclaimer:

This question reformulates and builds upon this one:

• Where's the proper (resource handling) Rule of Zero?

Answer 1

The type unique_ptr is less general than the phrase "handle", yes. But why shouldn't it be? Just one of your "handle" examples (say, the one that is an integer index), is precisely as general as unique_ptr. You can't compare one specific kind of handle with "all handles ever".

If you want a single, concrete C++ type (or type template) that is a handle without actually defining any specific handling semantics then... I can't help you. I don't think anyone tractibly could.