This post from Eamonn McManus shows a seriously geeky approach to generating and loading Java (byte-)code on the fly. Ingenious, without a doubt — but it reminds me of Coplien’s Advanced C++ Programming Styles and Idioms: There’s a whole chapter in there that shows how to dynamically load code in C++. I happened to read the book (which is from 1991) when I was already using Java (in 1998, I think); I remember how happy I was that I didn’t have to actually use it anymore. James Robertson is right on: It might be wizardry, but productive: no.