3.4.1 "Whatever Happened to Reuse?"

by Steve Adolph

While many companies justify their investment in object technology by citing productivity gains realized from systematic reuse, few have seen productivity increases. Software development economics don't generally justify reuse. Without reuse, why bother with object technology?

Ask most people why they are interested in object technology and more often than not the answer will be reuse. Nearly a decade ago, Electronic Data Systems performed an experiment in which they redeveloped a manufacturing system that was originally written in PL/1. A team of Smalltalk programmers received the same specifications and test suites as the PL/1 team had been given and proceeded to replicate the manufacturing system. The results were impressive. The original PL/1 system consisted of over 265,000 source lines of code (SLOCs), required 152 staff months of effort, and took more than 19 calendar months to develop. The Smalltalk system consisted of 22,000 SLOCs, required 10 staff months of effort, and took only 3.5 calendar months overall, a 15-fold improvement in productivity, attributed to the systematic reuse of software components (see David Taylor's Object Oriented Information Systems: Planning and Implementation, John Wiley and Sons, 1992).

Even though these numbers may appear inflated for everyday developers, this was still powerful stuff in the hands of managers desperately looking for a technological solution to cope with their project backlogs. It made sense that developers should construct programs from pre-built components rather than handcrafting programs line by line. The electronics...