Setters implement generalized locations for objects
associated with some sort of mutable state. A getter operation
retrieves a value from a generalized location and the corresponding
setter operation stores a value into the location. Only the getter is
named – the setter is specified by a procedure call as below. (Dylan
uses special syntax.) Typically, but not necessarily, getters are
access operations to extract values from Yasos objects (see Yasos).
Several setters are predefined, corresponding to getters
car) is equivalent to
This implementation of setters is similar to that in Dylan(TM)
(Dylan: An object-oriented dynamic language, Apple Computer
Eastern Research and Technology). Common LISP provides similar
Returns the setter for the procedure getter. E.g., since
string-ref is the getter corresponding to a setter which is
(define foo "foo") ((setter string-ref) foo 0 #\F) ; set element 0 of foo foo ⇒ "Foo"
If place is a variable name,
set is equivalent to
set!. Otherwise, place must have the form of a procedure
call, where the procedure name refers to a getter and the call indicates
an accessible generalized location, i.e., the call would return a value.
The return value of
set is usually unspecified unless used with a
setter whose definition guarantees to return a useful value.
(set (string-ref foo 2) #\O) ; generalized location with getter foo ⇒ "FoO" (set foo "foo") ; like set! foo ⇒ "foo"
Add procedures getter and setter to the (inaccessible) list of valid setter/getter pairs. setter implements the store operation corresponding to the getter access operation for the relevant state. The return value is unspecified.
Removes the setter corresponding to the specified getter from the list of valid setters. The return value is unspecified.
Shorthand for a Yasos
define-operation defining an operation
getter-name that objects may support to return the value of some
mutable state. The default operation is to signal an error. The return
value is unspecified.