This post originated from an RSS feed registered with Java Buzz by Geoffrey Wiseman. Original Post: Software Re-use and Varied Functionality Feed Title: Furious Purpose Feed URL: http://www.jroller.com/diathesis/feed/entries/rss Feed Description: Thoughts and experiences on technology and software. Latest Java Buzz Posts Latest Java Buzz Posts by Geoffrey Wiseman Latest Posts From Furious Purpose

It's pleasing to see this article on software re-use, with which I mostly agree. In particular, the assertion that the problem with code re-use at higher levels is typically with variability, not with the technical mechanisms that enable re-use.

Structured and object-oriented programming offer different and, in my opinion, increasingly useful metaphors for re-use. For instance, object-oriented encapsulation allows you to make a complicated operation seem simple in ways that are harder to accomplish with a purely structured software system. Ultimately, though, I have to agree with the author that re-use in the small is a problem that's been solved, with varying degrees of success, for quite some time.

Recently, I've seen a number of purported re-use attempts that were not particularly successful, and many of these were because the underlying functionality varied at the detailed level. At the highest conceptual level, two systems seemed similar, but in all the ever-so-important details, they varied. This ends up meaning that the potential for re-use was primarily at the semantic level, or perhaps as low as some high-level service interfaces, but rarely in the detailed functional level makes the re-use of larger components possible.

The myriad differences at the detailed level are not always easy to see from the perspective of a high-level business stakeholder, who may feel that the two projects are strikingly similar and that economies of scale should, thus, be possible. This can lead to some frustrating conflicts between perceived re-use value and actual re-use value.

I'm a happy proponent of extensive re-use of small components, particularly in a loosely coupled form that is easy to assemble in different ways, but larger re-use can be troublesome, and this is often because the problem and the solution vary in significant ways, even if those are difficult to discern.