Class Methods

  Class methods are declared using the CLASS METHOD command.

  A class method is a method which operates on an entire class (or a subset
  of a class), rather than on a single instance of that class. Any operation
  which deals with more than one instance of a class is a good candidate for
  a class method.

  In a class method, the self variable refers to the class object for
  that class. This means that class methods can access class variables
  directly. For example, in the previous section, the expression:

    ::class:currSelected

  was used to access the class variable currSelected. In a class method,
  we would instead use ::currSelected to access the variable.

  If a regular method is accessing class variables and methods repeatedly,
  it is worth exploring whether that aspect of its operation can be
  extracted and made into a class method. It is more efficient to access
  class variables from within a class method. Also, it often makes better
  sense from a conceptual design perspective to encapsulate, within a class
  method, code which repeatedly uses class messages.