Читать книгу The Big R-Book - Philippe J. S. De Brouwer - Страница 230

All refclass object inherit from the same superclass envRefClass, and so they get at creation some hidden fields and methods. For example, there is .self. This variable refers to the object itself.

Other common methods for R5 objects that are always available (because they are inherited from envRefClass) are the following, illustrated for an object of RC class named RC_obj:

 RC_obj$callSuper(): This method initializes the values defined in the super-class.

 RC_obj$initFields(): This method initializes the values fields if the super-class has no initialization methods.

 RC_obj$copy(): This method creates a copy of the current object. This is necessary because Reference Classes classes don't behave like most R objects, which are copied on assignment or modification.

 RC_obj$field(): This method provides access to named fields, it is the equivalent to slots for S4. RC_obj$field(“xxx”) the same as RC_obj$xxx. RC_obj$field(“xxx”, 5), the same as assigning the value via RC_obj$xxx <- 5.

 RC_obj$import(x): This method coerces x into this object, and RC_obj$export(Class) coerces a copy of RC_obj into that class.