There is a competition between Jython and Eclipse. Technically, the only thing they have in common is Java, but when I want to write some code quickly and Java is a requirement, I currently have two reasonable choices: full-blown Eclipse with refactoring, code completion, etc., or Jython.

The path of least resistance is Java on Eclipse. Eclipse makes it easy to generate Java fast. Static type checking makes me feel good: the code may not compile at first, but when the static type checks pass, I feel like I've accomplished something. Renaming things, even entire packages, is effortless.

With Jython, I have to refer often to documentation because code completion is not available. I have to manage import statements myself. I can't easily rename things. I have to write unit tests. However, I produce shorter, cleaner code in Jython.

So Eclipse wins, right? Not so fast! I expect other coders to read my code far more often than they modify it. Therefore, I prefer Jython on faith that readability is more important than generating code quickly.

Nevertheless, every time I've wanted to use Jython, I've fallen back to Eclipse. It's just too easy. I can't figure out whether the benefits of Jython really outweigh Eclipse. I've tried the Jython/Python Eclipse plug-ins, but they don't support the most important features that make Eclipse so easy to use.

On the other hand, when Java is not a requirement, CPython wins easily. The number of things I have to remember is significantly smaller when I'm writing CPython, so code completion just isn't needed. It's like writing prose. The seamless interaction with the command line makes unit tests, particularly doctests, fun and easy.