Prefactoring

2.2. Reinvention Avoidance

Once Tim and I understand Sam's system requirements, our first step is to determine whether an existing program provides the features that we need. There is no sense in re-creating the wheel if an existing wheel works the way we want. Our goal as developers is to solve the client's problem, not to just write code.

Sam had searched for a commercial program and did not find anything. It appears that he is in a unique business, so nothing has been written, which is not surprising.^[*]

^[*] Finding existing solutions can be problematic. Sometimes it can be hard to describe the solution you seek in such a way that Google? can find a match.

We suggested to him that the process of renting a CD is similar to the process of renting a videotape or DVD. He could purchase one of those programs and it would already have many of the features that he wanted. He decided that he would rather have his own custom program instead of dealing with the terminology and handling differences among CDs and DVDs. We recommended that if he decides to expand into selling CDs, we should investigate retail sales systems. A lot of functionality already exists in those systems that should not be re-created. If a preexisting solution fits into the overall system, at least that part of the wheel need not be recreated.^[†]

^[†] See Software Tools by Brian W. Kernighan (Addison-Wesley Professional, 1976) for the earliest discussion I have found on the issue of using tools to create solutions. ...