Blue Jay

http://www.bluej.org/

BlueJ is a closed source, no cost JavaLanguage JavaIde specifically designed for learning. It is fundamentally visual, you see all the classes in a project, and inheritance/composition relations displayed in a visual workspace. Also, there's no need to have a wrapper class for a main() method and I/O at all -- you can instantiate any object, any time, and those instances also appear visually on a workbench, and you call their methods directly via a context menu, inspecting the results. It hardly gets more interactive than that, and you can teach/learn OOP concepts and programming fundamentals without having to digress into API / support platform calls for a single second.

We had great fun playing around with BlueJ, but is there something like it for other languages?

MicroSoft's VisualStudio 2005 (VisualStudioWhidbey) offers an ObjectBench? just like BlueJay's -- except it's called an ObjectTestBench?.
There's always SmalltalkLanguage, which BlueJay is trying to become.
I'm not sure that's quite accurate. BlueJay is primarily a GraphicalProgrammingLanguage for JavaLanguage, built on a UnifiedModelingLanguage-flavoured "icons on strings" metaphor and intended for teaching purposes. Is there an equivalent for SmalltalkLanguage?

Can this be done on C++ without writing your own interpreter, or adding lots of metadata to the user code?

CategoryJava