Lava flow

AntiPattern Name: Lava Flow
Also Known As: Dead Code
Most Frequent Scale: Application
Refactored Solution Name: Architectural Configuration Management
Refactored Solution Type: Process
Root Causes: Avarice, Greed, Sloth
Unbalanced Forces: Management of Functionality, Performance, Complexity
Anecdotal Evidence:

“Oh that! Well Ray and Emil (they’re no longer with the company) wrote that routine back when Jim (who left last month) was trying a workaround for Irene’s input processing code (she’s in another department now, too). I don’t think it’s used anywhere now, but I’m not really sure. Irene didn’t really document it very clearly, so we figured we would just leave well enough alone for now. After all, the bloomin’ thing works doesn’t it?!”
Background

In a data-mining expedition, we began looking for insight into developing a standard interface for a particular kind of system. The system we were mining was very similar to those we hoped would eventually support the standard we were working on. It was also a research-originated system and highly complex. As we delved into it, we interviewed many of the developers concerning certain components of the massive number of pages of code printed out for us.

Over and over, we got the same answer: “I don’t know what that class is for; it was written before I got here.” We gradually realized that between 30 and 50 percent of the actual code that comprised this complex system was not understood or documented by any one currently working on it.

Furthermore, as we analyzed it, we learned that the questionable code really served no purpose in the current system; rather, it was there from previous attempts or approaches by long-gone developers. The current staff, while very bright, was loath to modify or delete code that they didn’t write or didn’t know the purpose

of, for fear of breaking something and not knowing why or how to fix it.

At this point, we began calling these blobs of code “lava,” referring to the fluid nature in which they originated as compared to the basaltlike hardness and difficulty in removing it once it had solidified. Suddenly, it dawned on us that we had identified a potential AntiPattern.

Nearly a year later, and after several more data-mining expeditions and interface design efforts, we had encountered the same pattern so frequently that we were routinely referring to Lava Flow throughout the department.

General Form

The Lava Flow AntiPattern is commonly found in systems that originated as research but ended up in production. It is characterized by the lavalike “flows” of previous developmental versions strewn about the code landscape, which have now hardened into a basaltlike, immovable, generally useless mass of code that no one can remember much, if anything, about.

This is the result of earlier (perhaps Jurassic) developmental times when, while in a research mode, developers tried out several ways of accomplishing things, typically in a rush to deliver some kind of demonstration, thereby casting sound design practices to the winds and sacrificing documentation.

The result is several fragments of code, wayward variable classes, and procedures that are not clearly related to the overall system. In fact, these flows are often so complicated in appearance and spaghettilike that they seem important, but no one can really explain what they do or why they exist.