## use_classes

### Synopsis

Defined in <boost/openmethod/core.hpp>.

```c++
namespace boost::openmethod {

template<class... Classes, class Policy = BOOST_OPENMETHOD_DEFAULT_REGISTRY>
struct use_classes {
    use_classes();
    ~use_classes();
};

}
```

Usage:

```c++
use_classes<Classes...> some_unique_name; // at file scope
```

### Description

`use_classes`, instantiated as a static object, registers `Classes` in `Policy`.

Classes potentially involved in a method definition, an overrider, or a method
call must be registered via `use_classes`. A class may be registered multiple
times. A class and its direct bases must be listed together in one or more
instantiations of `use_classes`.

Virtual and multiple inheritance are supported, as long as they don't result in
a class lattice that contains repeated inheritance.

NOTE: The default value for `Policy` is the value of
`BOOST_OPENMETHOD_DEFAULT_REGISTRY` when `<boost/openmethod/core.hpp>` is
included. Subsequently changing it has no retroactive effect.

### Members

#### constructor

```c++
use_classes();
```

Registers `Classes` and their inheritance relationships in `Policy`.

#### destructor

```c++
~use_classes();
```

Removes `Classes` and their inheritance relationships from `Policy`.