QtScript is also good for tiny things
Here's a quick example of why it's nice to have a script interpreter embedded in Qt: Plasma's KRunner has a calculator which used code borrowed from the KDE 3.x minicli. The old code started up the bc command line calculator then displayed the result - not exactly an efficient way to do things. I've just committed a change that makes it use QtScript and the code is trivial:
QString CalculatorRunner::calculate( const QString& term ) { QScriptEngine eng; QScriptValue result = eng.evaluate( term ); return result.toString(); }
This replaces 23 lines of code and is quite a bit more powerful. Nice!