Classes cannot be defined interactively (at least in Emacs under Linux).
classes are compiled for efficiency. squeak is by far not so efficient because it allows this.
cf. no way to create new classes at run-time.

• what you can always do when you need the functionality of a class is:
  • use a dictionary with functions. you can set

    myDict.know_(true)

    then it will work like a class (see sc-user mail repository)
  • another way:

    Def(\name, func) -> Do(\name, args)

  • one more:

    uniqueMethods

    hardly anyone ever uses them