Use Someone Elses

Cure for NotInventedHere. If you need a piece of code, you could write it yourself, thereby repeating the effort - and quite possibly the mistakes - of thousands of other programmers.

Or, you could

Download an existing implementation and
- Use it as it is, or
- Modify it to suit your specific needs, or
- Examine it, thereby taking some of the mystery and/or effort out of writing your own. Or you could
Use your money (if any), and
- License somebody's implementation, or
- Hire someone to implement it for you. Or you could
Read the academic literature and learn how existing implementations work.

You can't UseSomeoneElses code without their permission, and sometimes their active co-operation. Many, though, are eager to give it. Consider accepting.

See also OtherPeoplesCode.

Once, a few years back, I needed to sort some java objects. I thought, surely there are hundreds of good sort routines on the web. There were; unfortunately, they were all descendants of one program distributed by none other than JamesGosling. I say unfortunately because they all had the same bug: failure on equal keys, a case Gosling hadn't tested. Fortunately, I'd written sorts before and had no trouble diving in and fixing it. Moral: it's easier to reuse when you could just as easily rewrite. -- WardCunningham

What was the sorting algorithm, and was it appropriate?

Last year (2001) I needed to embed FTP functionality into a (Java) content management system I was developing. I had written my own set of FTP classes the year before, but no longer had access to them, so I Googled for a Java FTP implementation. I found a couple. The one I downloaded turned out to be a complete mess. The original implementer didn't seem to understand Java synchronization and threading very well, and the whole thing was just a hodgepodge. But it worked. A few hours of refactoring turned into something clean and shiny, that still worked, and I was spared loads of implementation effort. Moral: even if the code is ugly, it's often better to reuse and refactor than to rewrite. -- RobertGreayer