POTD: checking package name for Windows reserved words

Today’s project of the day is a little tool that checks problems in your package names that can bite you on Windows.

For backward compatibility with MS-DOS (which had ended its life more than 15 years ago!), Windows doesn’t allow you to create files/directories of certain names, such as “AUX” or “PRN” (see Microsoft Knowledge Base.)

This can bite those of us who develop on Unix — when you accidentally create a file or a directory of this name (say in the package name), it’ll be all right for you, but your colleagues who use Windows will not be able to build them. Worse yet, if none of your colleagues use Windows either, this problem can get unnoticed until you ship/test the code.

So I wrote a little tool that proactively checks for this problem. It’s an annotation processor that kicks in automatically, so you just need to add it in your classpath when you compile your source files. If you use a build system that can handle transitive dependencies (such as Gradle or Maven), you just need to use it in one of your libraries, and all the code that uses your library also benefits from this check.

My hats off to Microsoft for their rigorous commitment to the backward compatibility, and just one more reason why you should be always testing your Java program on multiple platforms…

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