BOOST_OPENMETHOD_OVERRIDE

Synopsis

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

BOOST_OPENMETHOD_OVERRIDE(NAME, (PARAMETERS...), RETURN_TYPE) {
    // body
}

Description

BOOST_OPENMETHOD_OVERRIDE adds an overrider to a method.

The method is deduced from a call to a method guide function with the overrider’s arguments.

The macro creates several entities in the current scope.

  • A class template that acts as a container for the overriders of the methods called NAME:

template<typename...> BOOST_OPENMETHOD_OVERRIDERS(NAME);

  • A specialization of the container template for the overrider:

struct BOOST_OPENMETHOD_OVERRIDERS(NAME)<RETURN_TYPE(PARAMETERS...)> {
    static auto fn(PARAMETERS...) -> RETURN_TYPE;
    static auto has_next() -> bool;
    template<typename... Args>
    static auto next(typename... Args) -> RETURN_TYPE;
};

where:

  • fn is the overrider function.

  • has_next() returns true if a less specialized overrider exists.

  • next(Args…​ args) calls the next most specialized overrider via the pointer stored in the method’s next<fn> member variable.

Finally, the macro starts the definition of the overrider function:

auto BOOST_OPENMETHOD_OVERRIDERS(NAME)<RETURN_TYPE(PARAMETERS...)>::fn(
    PARAMETERS...) -> RETURN_TYPE

The block following the call to the macro is the body of the function.

NAME must be an identifier. Qualified names are not allowed.
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