Although object-oriented code may be inherently more reusable than functionally oriented code, most object-oriented legacy systems were not designed with reuse in mind. OO code, due to the very aspects that make it desirable, tends to suffer from a wide scattering of the code that performs even a fairly simple task. It is considered to be good object-oriented programming style to write small member functions, which results in an OO system consisting of a large number of small modules. Through inheritance, a class may inherit one or more classes, each with its own associated methods, but few defined locally.

These aspects of object-oriented code underline the need for good, semantically based tools to aid in the understanding, and thus the reuse, of object-oriented code. The Patricia (Program Analysis Tool for Reuse) system, developed at the University of Alabama in Huntsville, identifies reusable components in OO code. To understand a program, Patricia uses a unique heuristic approach, deriving information from the linguistic aspects of comments and identifiers and from other nonlinguistic aspects of OO code, such as class hierarchy.