SOFTWARE DOCUMENTATION

If the design documents truly represent a complete design, the manufacturing team can proceed to build the product. In fact, they can proceed to build lots of the product, all without any further intervention of the designers. After reviewing the software development life cycle as I understood it, I concluded that the only software documentation that actually seems to satisfy the criteria of an engineering design is the source code listings.
There are probably enough arguments both for and against this premise to fill numerous articles. This article assumes that final source code is the real software design and then examines some of the consequences of that assumption. I may not be able to prove that this point of view is correct, but I hope to shown that it does explain some of the observed facts of the software industry, including the popularity of C++.
There is one consequence of considering code as software design that completely overwhelms all others. It is so important and so obvious that it is a total blind spot for most software organizations. This is the fact that software is cheap to build. It does not qualify as inexpensive; it is so cheap it is almost free. If source code is a software design, then actually building software is done by compilers and linkers. We often refer to the process of compiling and linking a complete software system as "doing a build". The capital investment in software construction equipment is low—all it really takes is a computer, an editor, a compiler, and a linker. Once a build environment is available, then actually doing a software build just takes a little time. Compiling a 50,000 line C++ program may seem to take forever, but how long would it take to build a hardware system that had a design of the same complexity as 50,000 lines of C++.
Anothe r consequence of considering source code as software design is the fact that a software design is relatively easy to create, at least in the mechanical sense. Writing (i.e., designing) a typical software module of 50 to 100 lines of code is usually only a couple of day's effort (getting it fully debugged is another story, but more on that later). It is tempting to ask if there is any other engineering discipline that can produce designs of such complexity as software in such a short time, but first we have to figure out how to measure and compare complexity. Nevertheless, it is obvious that software designs get very large rather quickly. Given that software designs are relatively easy to turn out, and essentially free to build, an unsurprising revelation is that software designs tend to be incredibly large and complex. This may seem obvious but the magnitude of the problem is often