Within a class definition (e.g., within an instance variable's initial value expression), instance variables declared in the class are part of the environment; the instance variable name is used directly to get a value, and set! is used to set an instance variable's value.
Instance variable values are accessed from outside an object with
the ivar procedure:
(ivar [class] object name)
(Square brackets here indicate optional arguments.) The name is not evaluated: it should be an identifier naming the desired instance variable. Private variables can never be accessed using ivar. If the specified instance variable cannot be found, the exn:object:ivar exception is raised.
If class is specified, the non-overridden instance variable value is found for the specified class. In this way, the value of an instance variable can be obtained even if it has been overridden in a derived class.
The uq-ivar procedure is like ivar, but the naming argument is
evaluated:
(uq-ivar [class] object name-expr)
The send abbreviation is useful for invoking methods:
(send object name arg
)
((ivar object name) arg )