I'm using JRebel with Scala and I'm quite frequently experiencing the need for restart of server due to the fact that JRebel is unable to load a class if the superclass was changed. This is done mainly when I change anonymous functions as I can deduce from the JRebel error desription: Class 'mypackage.NewBook$$anonfun$2' superclass was changed from 'scala.runtime.AbstractFunction1' to 'scala.runtime.AbstractFunction2' and could not be reloaded.
Is there any way, how can I design my code to avoid this? Does scala compiler take the functions, numbers them from one as they appear in source code?
The numbers that are changing refer to the number of function arguments. An AbstractFunction1 is a one-argument function, while AbstractFunction2 is a two-argument function. One way to work around this would be to curry or tuple your functions so that they're always one-argument functions.
And, yes, anonymous functions are automatically named as you suggested. If you insert a new anonymous two-arg function before an existing anonymous one-arg function, it will appear as if the type of the original function changed.