Class::XSAccessor implements fast read, write and read/write accessors in XS.
Additionally, it can provide predicates such as has_foo() for testing whether
the attribute foo is defined in the object. It only works with objects that
are implemented as ordinary hashes. Class::XSAccessor::Array implements the
same interface for objects that use arrays for their internal representation.

WWW: http://search.cpan.org/dist/Class-XSAccessor/