diff options
Diffstat (limited to 'lisp/emacs-lisp/cl-generic.el')
| -rw-r--r-- | lisp/emacs-lisp/cl-generic.el | 23 |
1 files changed, 20 insertions, 3 deletions
diff --git a/lisp/emacs-lisp/cl-generic.el b/lisp/emacs-lisp/cl-generic.el index 544f1fa140f..3bbddfc45a1 100644 --- a/lisp/emacs-lisp/cl-generic.el +++ b/lisp/emacs-lisp/cl-generic.el @@ -37,9 +37,26 @@ ;; Added elements: ;; - We support aliases to generic functions. ;; - The kind of thing on which to dispatch can be extended. -;; There is support in this file for (eql <val>) dispatch as well as dispatch -;; on the type of CL structs, and eieio-core.el adds support for EIEIO -;; defclass objects. +;; There is support in this file for dispatch on: +;; - (eql <val>) +;; - plain old types +;; - type of CL structs +;; eieio-core adds dispatch on: +;; - class of eieio objects +;; - actual class argument, using the syntax (subclass <class>). + +;; Efficiency considerations: overall, I've made an effort to make this fairly +;; efficient for the expected case (e.g. no constant redefinition of methods). +;; - Generic functions which do not dispatch on any argument are implemented +;; optimally (just as efficient as plain old functions). +;; - Generic functions which only dispatch on one argument are fairly efficient +;; (not a lot of room for improvement, I think). +;; - Multiple dispatch is implemented rather naively. There's an extra `apply' +;; function call for every dispatch; we don't optimize each dispatch +;; based on the set of candidate methods remaining; we don't optimize the +;; order in which we performs the dispatches either; If/when this +;; becomes a problem, we can try and optimize it. +;; - call-next-method could be made more efficient, but isn't too terrible. ;;; Code: |