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RedBarGreenBar is ShellEnvy

The TDD and XP communities talk a lot about red bars and green bars (failing tests and passing tests in tools like [JN]Unit). I suspect this is a poor man's interactive environment for statically compiled languages, what Lisp people call a read-eval-print loop and the rest of us call a shell. Support for XP/TDD is best when the language has an interactive top layer. Smalltalk IDEs had this insofar as there was no discernible compile step. Lisp, Python and Bash have this. Tools like VisualAge (which derives from Smalltalk) and more recently IDEA, attempt to coerce static languages into a scripting context. As Ward Cunningham puts it:.

They're complicated, and you have to learn how to work them - but boy, when you do, they make those languages start to feel like scripting languages.

The red-code-green loop in Junit and Nunit is a stab at interactivity and fast feedback. And one of the reasons IDEA is the best Java IDE on the planet is because it gets us Java/J2EE types further away from the C/C++ code-compile loop and nearer to an interactive coding environment.

March 25, 2003 11:24 PM


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