zl:1 - FTP

defwhopper
162
For example, zl: base is defined like this:
(defvar-standard zl :base 18. 18. 18. validate-base)
(defun validate-base (b)
(and (fixnump b) « 1 b 37.»)
See the section "Standard Variables" in Symbolics Common Lisp: Language
Concepts.
I
defwhopper
Special Form
The following form defines a whopper for a given generic-function when applied
to the specified flavor:
(defwhopper (generic-function flavor) (argl arg2 .. )
body)
The arguments should be the same as the arguments for any method performing
the generic function.
When a generic function is called on an object of some flavor, and a whopper
is defined for that function, the arguments are passed to the whopper,
and the code of the whopper is executed.
Most whoppers run the methods for the generic function. To make this
happen, the body of the whopper calls one of the following two functions:
continue-whopper or lexpr-continue-whopper. At that point, the before
daemons, primary methods, and after daemons are executed. Both
continue-whopper and lexpr-continue-whopper return the values returned
by the combined method, so the rest of the body of the whopper can use
those values.
If the whopper does not use continue-whopper or lexpr-continue-whopper,
the methods themselves are never executed, and the result of the whopper
is returned as the result of calling the generic function.
Whoppers return their own values. If a generic function is called for value
rather than effect, the whopper itself takes responsibility for getting the
value back to the caller.
For more information on whoppers, including examples: See the section
"Wrappers and Whoppers" in Symbolics Common Lisp: Language Concepts.
defwhopper-subst (flavor generic-function) lambda-list &body body Macro
Defines a wrapper for the generic-function when applied to the given flavor
by combining the use of defwhopper with the efficiency of defwrapper.
The following example shows the use of defwhopper-subst.