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Abstract

Reference counting has been used and described in abundance. We present novel ideas aimed at class implementations in library design: (1) In library design, generic classes can have variable size, such that an optimal decision for or against reference counting is not possible. We \emph{postpone} this decision to the place of class use. (2) In a context, where equality comparison for the case of equality is expensive, e.g., for exact algebraic number representations, we \emph{unify representations} whenever equality was detected, thus effectively caching equality tests. We explain an efficient implementation based on an union-find data structure. (3) Reference counting and \emph{polymorphic class hierarchies} can be combined reusing the pointer in the handle class for the polymorphism. A policy-based generic C\texttt{++} solution realizes all ideas. \emph{Standard} allocators manage all dynamic memory.